Craigslist all the way wismer, and you want to find bikes that were built in the 70's to early 80's. I'm tall as well and weigh 250. I bought a new 64cm Motobecane Cross which I basically did a complete build on afterwords with custom wheelset, carbon cross fork, longer crankset, carbon seatpost, etc. etc. But for kicks I bought two old 27" Schwinns off my local Craigslist. And when I say 27", I'm referring to the FRAME size. 27" translates to about a 69cm frame. BIG

They do not make production frames that big anymore, and aside from a custom build, you cannot go wrong with purchasing a bike from this era for fit. Put a long quill stem on I can't imagine you needing a bigger bike. A bike like this will also allow your wrenching skills to develop as you learn to work on it. (Something I think is fun to do but also necessary.)