What I do since we don't have (yet?) this minimap available in diplomatic screen, is to rename every starbases (including mine) I'm aware of.

The naming chart is quite simple:

XYz AB [ressource type - if needed] 1

XYz is for the generic type of the starbase:

EB for Econ Base (those who enhance econ )
MiB for Mining Base (ressource collecting bases)
MB for Military Base (no comment )
IB for Influence Base (any questions? ^^ )
TB for Terror Stars.

AB is the generic name of the race, 2 letters chart: see my Custom Ships - Ship Naming Chart thread for more info on this 2 letters chart.

[ressource type] (needless to say, without [ and ] ) is for morale, R&D, Eco, Military, Influence and Ascension ressource. It is for the MiB starbase kind.

1 is the number of the base for that given kind, then 2 if there is 2 of it for a given player (me or AI), ect...

About Econ Bases, I usually name it from the major star's name in the quadrant they are.

So that way, when negociating with AI, I can alway have a quick look on what kind of starbase they have. They are anyway usually not willing to trade for it, but it is alway good to have some intelligence on your current diplomatic partner (friend or foe).

I do also sometime rename some planets AI owns, those I might want to trade for/conquer.

I only play big maps, and yes, renaming for orientation is "feasible" for resource mines, but not for much else, IMO, because that would mean you had to be able to remember where all the stars were on the map or use and remembe some sort of coordinate-based renaming scheme.

The problem is that a given tradeable asset has an intrinsic value that is modified by location. Naming assets by type can't help you decide, for example, which gang of old ships to give away if you want the recipient to have any chance of using them in a way that would also help you out.