For soundtables, I used Thinst.sf2 and Thdrums.sf2:
Acoustic and Bright Acoustic Pianos for string leads. Flutes and Whistles for wind leads. Vibraphones and Strings for accents.
Patch 49/0 (String Orchest) and Patch 53/0 (Choir Ahh) for padding and POWER drumkit for percussions.
Ah, THFont. Has a few good samples but not quite my cup of tea...or coffee....
As for VSTis, I just used Fruity Reverb and Parametric EQ to clean and refine the sounds. Added a Flanger to the pianos to get it sound a little more distorted. I used Fruity Limiter for monitoring the audio levels along with level compression. Finally, I slapped Maximus on the Master track for mastering purposes.
I don't like using too much of those fancy synths and VSTi, since I generally don't know how they work. I just read them up on the Internet whenever I think I need to use them. 
Those are VSTs and not VSTis. The latter also has an instrument component, whether that be specialized instrument processors or MIDI synths or whatever.
I tend to use a crapton of these synths and VSTis, primarily to load SF2 files (via SFZ+ on Sonar and EXS24 synth on Logic).
Yeah, that exactly. At normal mp3 quality the music was over 90% of the game's filesize. (Read: twice as large as CtC)
I'm looking for the best way to compress it to a more reasonable size while maintaining as much of the original quality as possible.
This is the best I could come up with at the moment.
Usually normal MP3 is 128kbps CBR and doesn't take up much space (which is why so many use this format). If the sound file was THAT large chances are it is WAV (raw waveforms, uncompressed, lossless) and would obviously have to be converted for efficiency reasons.
I personally prefer OGG for game engines due to the need to license MP3 decoding with Thomson (...for commercial works and mass distribution, at least), however.
