I watched Avatar in 3D-IMAX twice. First time myself, second time entire family. Every one enjoyed it a lot.
Greatest visual feast as a movie. The main plot actually is pretty simple with the usual liberal politically correct stuff. But if you see past that flaw (if you count that as flaw) then this is perfect.
It would worth every dime you spend. There are three version out there, regular, 3D and IMAX 3D. You want to see the IMAX 3D version.