If I like St. Germain I'll like......

Try Thievery Corporation.

If you have never fooled around with these two sites, it could be worth a look. You input something you like, and it shows you other similar artists.The music-map result is graphical.
www.music-map.com
www.gnoosic.com/faves.php

A great way to explore new artists is to simply create a St. Germain Pandora channel. Just leave it on for a while and bookmark the artist when you hear a song that you like so you can later research their albums. You might also like Cantoma, Afterlife, Redlounge Orchestra.

Llorca
Aim - Stars on 33
Atjazz - Labfunk
Bugge Wesseltoft
DJ Cam - Soulshine
Cinematic Orchestra
Jon Kennedy
Kruder & Dorfmeister
The Dining Rooms
Tosca
Ulrich Schnauss
VA - Earth Volume 1 & 3 (LTJ Bukem Earth series)
Herbert - Secondhand Sounds
Wax Poetic

That's all older music, but I'm sure looking through the 'Recommended Items' on amazon/cdnow will lead to many others.

I'm enjoying Thievery Corporation but I wouldn't put them (pure trip-hop) in the same category as St. Germain. I love Cinematic Orchestra and will check out some of the other recommendations.