i agree tech victory is a little easy. i usually play with it disabled. half the time, i also disable influence victory. the AI usually doesn't pursue it unless they have a real clear advantage (played one game where the torians managed to grab 3 or 4 influence resources all clustered together... i was playing the Yor, and my colonies were rebelling. well, i had to take matters into my own hands

at the same time, quitch, you could probably stand to go up a difficulty level. disable the tech victory option. set up your race differently
this was actually something i was wondering about - methods of losing, and if an AI could (and ever would) beat you to technological victory. obiviously you can lose a military victory. you can lose an alliance victory. i've seen AIs gearing up to win an influence victory. if teh AI is programmed to play by the same rules we do, it should be pursuing victory rather than sustainance. personally, i think the deeper knowledge to tech vitory stretch should be more expensive. in fact i might be so bold as to say that deeper knwledge should be at least as expensive as any other tech (i think supreme miniturazation is the most expensive aside from technological victory).
maybe it would make more sense if there were more to the technological victory. in alpha centauri, you also had to build a wonder to get the victory. maybe something similar would be nice in GalCiv. but i think other things could be nice.
examples. as i understand it, 'deeper knowledge' is meant to be something akin to spiritual knowledge or wisdom. why not have this tech have a morale and diplomacy bonus? near omniscience being almost the ability to see the future might give a ship defense bonus. you could use this as a pretext for boosting the AI's interest in these techs, on the one hand, and also keep them useful in games where the tech victory is disabled. just some ideas. i've always got a million.
Quitch: it sounds like you're in a similar boat as I, though albeit at a higher difficulty level. slow down the tech rate, and consider disabling the tech victory all togethr. your strategy is what is making the game too easy. like me, it sounds like you prefer to bide your time. you end up more rounded than the AI usually does. maybe your tech level isn't the absolute hightest. maybe you don't have the largest military. mabye you haven't researched as many levels of missle technology. doesn't matter. doesn't matter because you've chosen to develop your empire more holistically. you'll have very strong diplomacy, trade, economy, industry, population, morale and research. when faced with a challenge, you can respond with just about any method the game is set up to offer, and you'll probably use all of them. in most of your games, you probably could have won in about two thrids of the time if you had focused your efforts more, but that would have left you vulnerable....
it's a gameplay style. at least, that's my guess. i play much the same, and i've found it's far too easy to win in any method. once i've built up my perfect empire, i have the industry to produce any number of influence bases, buy any mining base, create fleets unsurpassed, or research a technological victory inside a year. but this usually consists of taking a back seat to the first 3/4 of the game and doing everything i can to avoid conflict, only acting when it's an obvious necessity. that is a personality. in fact, it's pretty close to MY personality.
maybe it's time for some role playing, eh? play as the noble altarians; always do right, and don't ever let the smallest sin go un- smashed into oblivion. most of the races have a personality of some kind. run with it.
for example, in the game i'm finishing up now, i'm playing the terrans. you look around the world right now, and it's pretty messed up, especially due to our capitalist economy. our world has enough resourses to take care of everyone, but because of the economic system we use, resources are converted into wealth, which accumulates in fewer and fewer hands. as this happens, people become more willing to break laws and hurt one another to get an ever smaller slice of the earth-pie, i.e., evil. but the introduction of hyperdrive opens up the galaxy to capitalist expansion. the economy explodes. wealth abounds. in times like that, people are more moderate. i.e., neutral.
so there are my terrans. they get 25% bonuses in diplomacy and trade. i pick the merchantile party. i buy boosts in econmics (+30, 4pts), research (+10, 2pts), morale (+10, 1pt), population growth (+10, 1pt), luck (+25, 1pt) and military production (+1, 1pt). i name my empire the terran union (mostly so i can title my ships Union Star Ship, or USS). the terran union is a society of shrewd business people. think Brave New World. the Cardinoids and Dark Yor start very close to me and the Drengin. even in the game i'd know they were both doomed. they can become dinner for the drengin, or the Terran Union's gammas and deltas (literary allusion - if you don't get it, read the dang book). i've all ready researched enough that when i invade them i can even use info warfare. i maxed out my trade early to make everyone like me at least a little, and pursue diplomacy vigorously. so while i'm only producing a small number of 'duds' (a small size space ship with 1 stinger I and 1 ion drive), no one hates me enough to go to war with me. well, i should say, to also go to war with me. just about everyone is at war with someone else, licking their wounds, or rearming. the yor are the first to drop, and they surrender to me. then go the korx, surrendered to the previously meek altarians. the drath were pretty quiet until they found a Ranger. then everyone started cowering. meanwhile the drengin had been researching up a storm on their 3 little planets, and they took over the iconions. they reconstructed quickly, and are now the only rivals to the drath. the great war breaks out. the drath forge an alliance with the other good civs and eventually manage to wear down the drengin (their allies receiving a little financial backing from muoi). during the years of war, the thalans had amassed quite an armada. they attacked the altarians, and everyone counter-attacked. even the arceans jumped in, decrying the need for galactic balance. by this point i even had a military advantage, though only due to a spin control center. the thalans gave up to the arceans, and i started making preps. you see, the other 4 remaining civs had forced a common alliance. i hadn't allied with anyone, but had close relationships with all 4. i could have easily chosen a diplomatic victory....
but with my network of fully developed military bases and armada of completely decked-out warships, where's the fun in that? the ultimate capitalist logic: if you can't find a new market, conquer one.
is anyone else still noticing unusual behavior for the number of trade lines? i can't seem to get more than 12. i maxed out the trade techs early. after that, neutral shipping didn't raise it, nor did the UP law. i'm glad i didn't waste ability points or anything...