Well, we ended up getting two of these and beside deciding whether to get AppleCare or not (you probably should particularly for the steel version)
Aluminum vs Steel
Well, there is a huge markup if you decide to go steel, but it is shiny and looks really nice. Net, net I would say go with Aluminum if you are going to be upgrading a lot, but if it is a fashion piece (think Valentines Day, the the steel makes sense).
What Band to get
Well, I think there are a bunch of different ways to go, but the really elegant look is the solo loop. The main issue is that you have to really get the fit right. For instance, I used their measure trick and figured a size 6 was good, but when I got the band, it was really a size 5 that fit. The elegant look is really the silver buckle particularly if you have the steel watch. It just looks like it all goes together.
Screen Protectors and Cases
you also have to think about getting a screen protector. Now some folks won't want one because they take good care, but I've scratched my watch and struggled with bad protectors:
The simplest kind are basically thin plastic sheets that go over the watch. Since the watch is so curved, you can't put a glass protector like with an iPhone, so the ArmorSuit is one to try.
For those of us who are going to ding the various side, having a transparent case is nice for sports and other times you are going to be outdoors. I've had a bunch of TPU cases and at $4 each they are cheap if ugly protection. Finally I've also had a protector that has a TPU on the back and then some thin plastic on the front. The main problem I've found is that you get moisture into the watch and sweat kind of beads in there which is kind of gross.