If you're going to be using aero bars, then your long arms may not make much of a difference compared to your torso length and your flexibility. For a road bike, for example, you might want a longer reach because of your long limbs than you would on a tri bike. With your inseam, you probably want to look in the 54-56cm range. WSD may or may not feel comfortable to you. If you aren't getting a tri/TT specific frame, then a WSD bike could let you get a shorter reach to your aero bars without a huge amount of saddle to bar drop and without putting on a tiny stem. That may not feel so comfortable riding around otherwise. It depends on how you primarily want to use the bike. You might be able make some minor changes to a comfortable road bike fit to make it a decent setup for an aero position. Of course, you don't even have to start out thinking about aero bars at all, but if you think you'll get serious about triathlon, then they are a great way to shave off some time.

I'm bringing this up because I have a pretty long reach on my road bike. I cannot make it a decent setup for use in a TT without changing several parts and making my arms stick out too far in front of me and making me unstable. That's ok, because I don't do a bunch of TTs, and if I do in the future, I'll get a TT bike that is a different size and build. If I wanted to do tris primarily instead of road racing, then I'd be kind of out of luck with the bike I have.