Multi-zone or integrated amplifier?

I currently have a Melior A/V control center with a Museteax CAS-10 amplifier. The main speakers, because I have a small space, are a set of apogee ribbon monitors. In addition, I have a/d/s in-walls in two adjoining rooms (kitchen and dining rooms). Although the apogees are in the main room, we do sometimes play music throughout the floor. The 3 rooms are all connected and the music is more for background.
I'm thinking of replacing the museatex products for an integrated. I've also enjoyed listening to my friend's B&W 805s speakers. I'm considering the Bryston B100, the Krell KAV 400xi or the Classe CA 2100. I've read that the pairs very well with the B&W's. Also, would a 100 watt integrated be better than a multi-zone, since it is generally the same source being played througout the listening area? Could also use suggestions on a good speaker selection switch.