a variety of smaller species is more interesting than a couple big fish. A BGK and a group of silver dollars would be sweet though. My 125 houses severums, silver dollars, Colombian and white skirt tetras, kubotai botia's, a few yellow Lab's just for color, and a big old Synodontis eupterus. Also a zebra knife fish that I never see unless I strip down the tank.
The 220 has 6 species of Tanganykian cichlids (38 total), a group of M. parva rainbows, a couple of Tang spiny eels and a group of Synodontis petricola. Also a number of BN, I have those in just about every tank now.