Maybe I've missed it before, but I don't think I've ever seen anyone mention an Advanced 3.5e. IMO this would make more marketing sense than a 3.75e. I'd be willing to be more people would be willing to buy into an AD&D 3.5e set of books that would essentially be a 3.75e with minor rules tweaks and the inclusion of all the "advanced" rules of Character Rebuilding, Reserve Feats, Skill Tricks, and the like. I don't think, however, that it should include things like Incarnum, Psionics, ToM, ToB, etc, which I see as being outside the "core" of D&D in general.
Here's a vote for AD&D 3.5!