Hmm ...
Would you mind providing a list of what instruments are allowed? I'm not familiar with band, and different places may differ as well. Please forgive me if this sounds daft, as I have only had experience with orchestras and not bands.
I'd suggest you first cross off anything that you definitely cannot see yourself doing. I would not play a cello, for example, because it's huge. Nor would I play any large instrument (apart from the piano or keyboard) as I wouldn't be able to support it.
Then remove those that would require a lot of knowledge to play. Violins aren't something a person can take up easily.
You will probably be left with things you don't mind doing and will not be difficult to learn. Then pick the instruments that seem to be ones you would like to learn afresh, or may be suitable to your skills.
The only ones I know similar to the piano are the keyboard, the xylophone and the glockenspiel. I did quite well on the latter two when I was younger and picked it up with ease. It was like playing on the keys of a piano, only my "fingers" were little sticks, so to speak. I really liked it. I have always wanted to learn the flute though. Ah well, can't have everything.
Anyway, hope you can choose something you'll like.