In my opinion, Boost.Graph is a badly documented and over-generalized mess, LEMON is really much more user-friendly. And the fact that Boost didn't provide a certain graph algorithm made my choice definite. Boost.Geometry looks slightly better structured than Boost.Graph, but I have never really used it yet.
Concerning Thor's triangulation, I wrote you a PM saying that you should send me an example reproducing your problem. You have not answered...