Check out Spokes, Etc. right there in downtown Vienna. I've found them incredibly helpful. I too am a fairly new rider (about a year and a half) and also tall and heavy. I bought a road bike from the get-go because I knew I wanted to ride long distance and started training for a century from the very first day I bought it. That's not to say a road bike is best for you. I don't know enough about the different kinds of bikes to give you any advice there.

I will, however, echo what some others have said -- I, too, kept breaking spokes on my rear wheel. When I broke the third one in a 10-day period, I took it back to Spokes, Etc. and told them my problem. They, too, were kind enough not to tell me it was because I was too fat. They just said that bike (Specialized Sequoia) didn't come with very good wheels. They replaced my rear wheel with a sturdier one, and I haven't had a single problem since. (Now, watch, I'll break a spoke on my next ride after saying that).

And, since you're in Vienna, you probably already know about the W&OD trail -- a wonderful, wonderful place to bike, regardless of if you have a hybrid, mountain or road bike. 45 miles of nice, smooth pavement for riding!