Maybe more hull sizes and customisable parts and more AI tweaks anything else also you have to say bump for this to appear in the recent posts

I detailed game manual, that will magically update itself when things change after each patch

A more involved storyline/branching scenarios....the SP campaign is pretty lame in the base game.

Mine are (in no particular order):

A new race, with their own new styles of hulls and parts.

Map Editor feature (like the AP expansion for gc1)

The Army Raising feature Brad mentioned in a journal

A threat option in the diplomacy system (Pay me 1000 bc for this new Influence base you set up outside my star system or be destoyed)

To play as the Dread Lords

I would agree with most. Havinge at least 1-2 extra hull sizes would add to the end play. I especially think the aspect of more variied diplomacy is despretly needed; (threats, alliance controls - i.e. war aspects, talk between civs on switching political or ethic types with and without pressure, etc). And, I think would be far better, different ship types and components - i.e. different ship hulls for each race, more component options, and maybe even more races to choose from (whether or not you can play them all). Tactical combat control would be great, especially if you have a smaller fleet but may be inflicting slightly more damage - (i.e. control your ships to fire on one more damaged first, especially if its bigger an/or more heavily armed).

1. Another vote for 'better' diplomacy. Better meaning deeper and more varied (the above post sums up some of the things I think would be nice on this front), as well as the AI being more pro-active and varied in its proposals. Basically a move away from the diplomacy paradigm of all 4x games i.e. just a way of trading techs and money.

2. Heroes. Or rather, 'characters'. There is little point in adding something like this if it is only along the lines of '+2 ship weapons' - I can just install a bigger gun instead. I mean a model of character development and creation to simulate the range of personalities one gets in an epic space opera, adding voice and personality to key events. I want Londo Molari in my retinue damn it!

3. A meaningful espionage portion of the game. I gather this is in the next expansion anyway. This should be another valid path to victory ratehr than an interesting distraction.

4. New races/Better distinction of existing races. Either way works for me if the team find a way to genuinely make each race play differently via unique game mechanics, units etc. +20 production just doesn't do it for me I'm afraid.

5. Optional sidequests that pop up from time to time. All helps to make every game an original story.

I think most have been mentioned already:-

Better diplomacy:- threats, more layers of treaties & trade deals, more involvement by UP - trade embargos for aggression, etc.
Better AI to be more challenging.
Better planetary invasion tactics and graphics (sry, but the invasion screen is fairly lame)!
Expanded tech tree, esp. for planetary improvements and Starbase enhancements.
More random events:- esp. major events that force you to rethink your strategies (maybe giant space blobs attack planet x, etc)
More 'stuff' in space:- blackholes, asteriods, ion storms (?) etc
Espionage:- as already planned.

This would get my cash

Well here is what I would like to see

1: Asteroid fields that you can mine for resource bonuses.
2: Planet specific races like in space empires 4. You would have to research other techs in order to take over an ocean planet if you were on a gas planet.
3: Allow you the ability to colonize class 0 planets. Could build mines to increase money production.
4: Possibility to play on even larger maps. ( I think it would be kinda interesting )
5: Expanded tech tree. Include more techs in all the areas.

I would only pay for a SP expansion if it included a large campaign. I like most of the game mechanics as is, so I wouldn't need to waste money on making it better since I have so little to begin with.

Improve diplomacy.. add more planets types and structures.. more events.. more AI.. several generic AI's that we could assign to minor races or created one....

Espionage..

Larger tech tree

more ship stuff.... I already voted yes ont he ship specific expansion.. but I would pay again for more...

The AI needs improved slightly for when they are at war. They leave their constructors and freighters unguarded as they travel. That makes way too easy of a target. Also, they don't attack my freighters. Instead, they go after my most powerful fleet.

Also, being able to name your ships and planets is great, but why not be able to name weapons/shields/improvements/everything else?

What would I pay good money for? Hmmm...how about the addition of the one thing that I was most dissapointed that GC2 didn't contain. Artificial Planets. Don't get me wrong, the new Tech Tree is nice and all, but there was a lot of stuff from the old GC1 Tech Tree that I was really hoping would be carried over and expanded, that wasn't. Artificial Satelites/Planets were the two I most wanted to see carried over and given a reall mechanical effect. Personally, I'd like to see you be able to "attach" Constructors to stars (that have fewer than five planets orbiting them) and begin construction of an artificial planet (maybe have the technology come off of Massive Scale Construction or...the last industrial technology, I can't remember the name of it). 24 more constructors and 25,000 bc (or so) later, you'd have yourself a shiny new planet to colonize. You'd probably want to make every artificial planet be a solid, un-terraformable class 10 for balance and common sense reasons. There are several problems with this, of course, and probably many of them are the reason something like this was never done, but...hey, that's what I want. Okay, I realize this is horribly wishful thinking, and not really in the spirit of the rest of the comments thus far, but a man's got to say what a man's got to say.

More realistically...Ai improvements would be nice (I'd prefer the AI played more organically), but are really not that big of a deal to me. My real request would be vastly improved and expanded diplomacy options. Much of that being that which others have already mentioned. The ability to threaten, politely or otherwise, other civilizations. Better trading (both with freighters and on the diplomacy screen). More peace-time options, better embargo-type options, more dynamic alliances. More relationship types (more than just War, Peace, and Alliance) like, I don't know, "favourite trading partner," or maybe just have the various stages of respect (Hostile, Nuetral, Freindly, Close, etc..) have more mechanical bonuses, rather than just being arbitrary names (that, admittedly, affect diplomatic trading to some extent). The United Planets is great and all...but it doesn't do anything. It would be great if it met more often/could be summoned by any civilization (player or otherwise) for a specific set of reasons (like, perhaps, new galactic emergencies), if it had more options for affecting civilizations (galactic embargos, war summons, yadda yadda), and if you could vote on multiple things per session (not just setting up a zoo and then going a way for a year).

Automatic civ-specific trade goods. (for example, the Terrans automatically have three things that no other civilization has or can research, let's say Cheese, Cockroaches, and Ceramics.) Each civilization has their own, unique Civilization Trade Goods that provide unique bonuses they can trade as they see fit. Just, generally, anything to further differentiate each race from another. Looking different than the other guy just isn't good enough anmore. Maybe cultural baises beyond what there already is. For example, maybe the Terrans get a discount (say, 15%) on researching Mass Driver-based weapons technologies and Influence technologies, while the Drengin get a similar discount bonus on energy weapon techs and invasion techs. Altarians get a discount on Diplomacy techs and Ethics techs...you get the picture. Maybe unique civ-specific technologies, like Advanced Holographics (don't ask me what bonuses that would grant) or something that only the Terrans (or whoever) can research...but only one or two per civilization so as not to get out of control.

Many, many more random events and (most importantly) them not completely shutting off the second you choose an ethical alignment (I hate that!).

There's more...but I think I've given enough unusable suggestions for one day.

Meaningful espionage - you can send a spy to a planet to stir up trouble. You can send a spy to a planet to get it to flip over to your side - you can send a spy to a fleet and get them to flip over to your side.

Homeworld Cataclysm had an interesting feature - you had a chameleon ship that would appear to the enemy to be one of their ships. Useful for espionage.

Invisibility fields. You can make your ships invisible for X number of turns (power drain is high for invisibility fields, only huge ships can have them)