They will let me try out any weapon they have. I really don't like .45s. Too much time to regain target.
What's the most likely purpose? In my view, a conceal piece, what is most important is that you can get the thing out and present it. After that, were you to actually need to fire it, we can argue all day about calibers, barrel length, etc. but, first and foremost, you gotta be able to get a hand on it and get it out.
Ideally, they will let you try holsters, too. If so, figure out where you want it to be and look at a titanium spur-less (no hammer) .357. They might be the smoothest thing I've tried from conceal in terms of snagging, light weight and a damn good punch if you gotta use it, man or beast. Simple operation. Downside is no safety. Upside is double action so, it's a deliberate thing.
I'm still thinking the MP5 and a parka. I mean, so it's a bit much in summer...you'll get used to it...