Welcome!
Blackberrys can be GREAT tools and are very easy to grow attached to as most "crackberry" addicts can tell you.
If you intend to use the phone portion a great deal I would suggest the 7100 or the 8700 for ease of use. If you intend to use email more frequently, almost any model would work equally well. If you're interested in the newest and greatest gadgets, I would definitely suggest the 8700!