I would likely go as follows:
AV2
PWS-75
TPMC-10 (theater)
TPS-2000 (in at least one sub zone)
12 button keypads in other rooms
ML-500 in living room - VERY good remote, not buggy like Pronto can be, integrates awesome.
PAD-8 for audio distribution
C2-Enet-1 (or 2) card for TPMC-10 & e-control interface
Connecting Block - Like Xantech CB-18
Antenna for XM radio
A bunch of IR emitters
A bunch of 232 cables or custom fittings for it
A bunch of audio interconnects - custom is MUCH better in a rack!
I would definitely allow for your zones 4 & 5 to be able to listen to the XM tuners and home audio and keep it as part of Crestron. Consistency is the key to make it so that everyone in the home can use the system. Different remotes all over, or completely different systems, like being forced to use a directional IR, non-logic remote like a Pronto can really screw up the system.
Might want to consider cable music for an audio source, if you want, as well as FM radio. Neither are as nice as XM though, but have their place. Also, what about CD/DVD? Do you have a digital jukebox like a Audio Request you are considering?
Go w/Radio RA - Make sure you get the Lutron RS-232 interface.
Most of all - don't forget to get enough wires and conduit where you need them for future upgrades. Nothing is worse than wiring up a $5,000+ plasma, then finding out you can't display everything you want on it, or control it because you forgot to run the right wire and can't add it in later.