Your path is really a function of the type of shooting you will be doing. If you expect to get into micro/macro photography, get the R1C1 kit which includes the SU800, a pair of SB-R200 units, and all the related accessories.
If larger sets are of interest (portraits, groups, etc.) you will get more use out of a couple more SB900/700 units, and perhaps some light stands to go with them. SB800s are no longer made, and I heard recently that SB600s have also ceased production.
Unless you are using remotes at great distances, or shooting around lots of obstacles, you won't need to get into Pocket Wizards at this stage of your photography.
Hope this helps a bit.
HBB in Phoenix, Arizona Nikonian Team Member
Photography is a journey with no conceivable destination.