Barbs are definitely the first thing that came to mind when I think of tankmates for a RTS. I think I would stay away from too many bottom dwellers but I think most "peaceful" fish would work as long as they are fast like danios or certain tetras. It really depends on what you want but I would stay away from a pleco of a pair of smaller territorial cichlids, which also stay near the bottom.
But anyways if you dont want barbs Id go with a decent school of tetras, rasboras, or danios...and then maybe a gourami.. this should work....