I have community tanks with many different types of dwarfs in them, so I'd have to disagree on that point.
There are tons of fish to choose from for your 55. Some examples: Angels, kribensis, bolivian rams, nannacara anomala, laetacara curviceps, keyhole cichlids, apistogrammas, Boesemani rainbows, turquoise rainbows, cochu's blue tetra, kerri tetra, purple passion danios, harlequin rasbora, pork chop rasbora, marble hatchets, peacock gudgeons, kuhli loaches, zebra loaches, orange lazer cories, false julii cories, clown pleco, pitbull plecos, leopard frog pleco, farowella cat, and panda garras.