Thanks guys. 6 it shall be.
I dig the clean, relatively-simple look of Timoe and MustardTent's CPs in particular, so that's the general direction I'm taking. With that in mind, I'm going to do 2 programmable ball-top sticks, a spinner, trackball, and 6 buttons each.
Now my only remaining decisions are on admin buttons and whether to do all the flashy LED stuff. My wife likes the lighted stuff, and I dig the "coolness" factor, but it just doesn't speak to the classic arcade gaming I remember (Tron excluded of course). Perhaps my memory's fading...

Chris