It is great to see that you are willing to get a 55 gallon or bigger! I would honestly get the biggest tank (within reason) that you could afford/store. At my Petco, it says the minimum number of gallons that you need for that species. But, you can never trust the pet stores, so whatever it says they need, I would go bigger.
~ Fireheart ~ Spikefin ~ Male Bettas ~ Dalihla ~ Lizzy ~ Female Guppies ~ Sir ~ Boss ~ G6 ~ Prayer ~ Male Guppies ~ Squirt ~ Male Dwarf Gourami ~ Reginaldo ~ Regilina ~ Strange ~ Stranger ~ George ~ Mystery Snails ~ Zeus ~ Poseidon ~ Hades ~ Hermes ~ Apollo ~ Serpae Tetras ~ Bristol ~ London ~ Beverly ~ Female Platies