I would suggest buying the trees pre-flocked. The cost is a bit higher, but the assembly time is dramatically reduced. And you get playing that much faster.
I use the Woodland Scenics trees exclusively on my game table and they hold up fairly well and they look very nice as well.
The only problem that I have found with them is that sometimes the pins in the base of the trunk break off and the treek will no longer attach to its base. The pins can be replaced with any thick metal pin or finishing nail cut down to size.