Isn't most of Florida flat. So, perhaps the fixie isn't a bad idea.

I seem to end up with hills wherever I go, so at least some gearing is nice. Plus, when towing a trailer, I'll often find myself dropping a couple of gears.

Each person is different, and as HardyWeinberg suggested, choose something that you like, and fits your goals and personality.

I've ridden an old steel road bike for decades. Recently I've expanded to a couple of mainly road bikes. But, the old road bike is still my go-to bike for many things.

I do have a sleek CF bike, but I wouldn't use it as a campus commuter (too much risk), and don't really want to tow a trailer with it (very much).

The old steel bike is good.

How big of an issue is RAIN?

I usually don't use fenders much. Even my "rain bike" is currently fenderless, but that may change. They might be worth considering in certain environments. Fender clearance might be important.