actually, i'd suggest a 20g long tank. it's not humongous, it's not teeny. please don't get a hex tank, they may look interesting by all strange-shaped tanks are pains for a newbie! 20g tank, coupled with 20lbs of gravel, enough plants to make the 'scape you need and any other things (driftwood, rocks, caves, etc) you or the fish you choose might want.
and you say you want Tropical fishies? ^^ my favourite way of deciding what to go in my tank is pretty much
1x2 Spotlights/10x1 Schoolers/4x3 Scavengers per 10g, it works quite well in terms of stocking and seems to agree with fish territory, water parameters, and the like.
so, for a 20g tank, you could have
two Dwarf Gouramis, ten White Cloud Mountain Minnows, ten Neon Tetras, and eight Kuhlii Loaches the Gouramis provide that large, puppy-fish eye-candy lots of people like, the Minnows and Tetras add color and activity, and the Loaches keep the tank clean and give the occasional dance-of-insanity across the tank front that's guaranteed to make anyone laugh.
just ideas, you should really listen to your instincts on what fish, what tank, and what-ever you want!
(but let the tank cycle and don't add all the fish at once!)