With a tank that size I would go with frontosas. I know they are probably the most common of the tanganyikans in the hobby, but there is a reason for that. Absolutely stunning when they reach maturity. My friend has a 7 - 8 yr old male that makes a fantastic cenrepiece for his tank.
You could add almost anything else from the lake in with them (except tropheus). Some julidichromis for the rockwork, leleupi's for a splash of yellow, cyps for the open water (as long as they are large enough to avoid becoming frontosa food), and round it off with some syno cats. I'm envious!
Check this out,
http://www.cichlid-forum.com/articles/
Lots of good info on fronts, tropheus, "cookie cutter" tanks, etc.