32GB 3G, Black. I was debating about the size and 3G but, at least for today, I have decided that I want 3G for travel and I think while I might not always need 32GB, I rather have it than not. I have a 16GB 3GS and found that I had to manage what was loaded. I had rather not have to think so much about syncing.
As for the 3G vs. Hotspot - I have a hard time now managing my phone's battery particularly when I travel. I hate running around wherever looking for an electrical outlet (or carrying extra juice). And since you don't have to sign a contract for data, that's a plus. I'll only turn on a 3G plan when I need it.
Verizon or ATT: I think I am going with Verizon. In my overall experience, Verizon data is just more consistent. ATT can be great and then literally disappear around the corner. If I find I have to travel internationally, then I'll Hotspot it.