Maple is my favourite. We have 4 maples on our property that I regularly "prune" for use in the smoker.
Because the prunings are only 1" diameter or so, I use them with charcoal. I've found they need a few months to dry out nicely (kept under cover). If I leave them too long, and they get really dry (like 2+ years) they don't seem to have as much flavour in them.
I also strip the bark, as it seems to have a slightly bitter smoke when the bark is still on.