A stab in the dark, but reminds me of either Heliconia or some kind of ginger family member like Alpinia zerumbet, Hedychium, etc.

I googled some pictures of heliconia. It's hard to tell, but the leaves look similar. My plant has no flowers, of course. And one species requires the opposite light/watering than the other, so I don't know what to do. I had this plant in our sun room which gets filtered, indirect light all day, and the leaves were yellowing and dropping off, so I put it in a room with less light, and I think it got worse. I recently re-potted it and am now going to try it in a room with bright sunlight.

It's a heliconia, probably Heliconia psittacorum which they sometimes sell at our Home Depot and Lowe's.

How 'bout hedycium 'Velvet Leaf' costus?

The costus stalks are usually spiral. I just looked at my Heliconia psittacorum and these are not the same nor is the Alpinia zerumbet and it relations as the leaves in your plant seem to originate at the base of the stalk rather tan 'off of the stalk'.
Suggest you search within the Calathea species... but be warned, there are lots! Possible match could be Calathea allouia.

Wow....any suggestions on care for Calathea allouia or the others mentioned?

well I'm sticking with Heliconia psittacorum, in which case it would thrive in hot humid weather with partial sun. The more sun it gets, the more water it will need. They will not overwinter in zone 9, not even in an unheated garage, in my experience, despite what the tag on the plant says. So it will have to come inside the house during cold spells.

Heliconia schiedeana?

Here is a link that might be useful:

I tried to edit my post, but couldn't, to say that you may have to wait until a bloom appears, since the leaves could be attributed to many 'familiar looking' plants.
Presently, our Heliconia psittacorums and Heliconia schiedeana are in full bloom and have been for the past few months, but am not sure when they bloom in your area of Florida.
If, it is a Calathea, they seem to thrive on neglect, in that they only require watering when it is extremely dry. As does Heliconia psittacorums and Heliconia schiedeana where here they receive absolutely no additional water during the dry season that last from Jan-May... in our area at least.
Obviously, none of the above don't like the cold.
Good luck.