Sounds like a great plan. I am going to do the same but build my L/C/R's. I still think I am going with the studios =P
Sounds like another great plan . Stand mounted speakers can certainly offer more placement options.
However, unless I already have something to put stand speakers on (bass bin, cabinet, etc), and its a standard vented design, I most always choose the tower version:
1) No speaker stand to build
2) "Free" bass extension
3) More lower bass sources for room smoothing