Those 360's s/b sweet! I've never used 'em, but think I'd get 'em if I did another cab. The microswitch joysticks get pretty 'clicky', especially when I'm playing Robotron. I use Ultimarc's T-stik + which allows u to switch between 4/8 way w/o going into your CP. This is a nice feature, I don't know how the 360 switches between 4/8 way. I think the Ultimarcs work great when playing classics that prefer 4 way control. Again, I'm not sure how the 360 switches between 4/8 way, but expect it would get old fast if you had to go into your CP everytime you had to switch. I decided against a dedicated 4 way only because I didn't want 3 joysticks on my CP.
Regarding the spinner, I would mess with whatever you are using to design your CP to see what arrangement works for YOU! I enjoyed spending time in Paintshop Pro arranging my controls & switching colors around until I felt I had a CP I could live with. If you spend time planning, chances are you wont be dissapointed with your results! If you don't have PSP, use cardboard or draw it on paper, and look at lots of examples of other peoples designs to get ideas.
For buttons, I used the I-PAC encoder which includes a 'shift' button. This let me keep the # of buttons on my CP down to a minimum. People only need to know which buttons to put a coin in, start a game, and escape out of a game. I handle eveything else (cab admin). I really didn't want a lot of buttons on my CP so the Ultimarc 'shift' solution worked out well.
Can't wait to see some pics!