I've never really noticed any drop-outs with AE or Apple TV. The flat I live in is pretty well soundproofed, so I think there may be thick dividing walls. I can only pick up 4 other networks despite there being about 100 other flats around me.
An ATV will allow me to use Spotify via my iPod and it also lets people hook up their ipods/iphones via Airplay. If I had an ATV in our guest room I imagine people would use it, whereas I'm not sure they'd be comfortable using a PS3 or Sonos unless they had one themselves.
Our living room/kitchen is open plan, and there are doors onto the balcony, so I only need one source to cover that area. I can't put anything in the bathrooms (such as in-ceiling speakers) as the boss would kill me! So it just leaves the 2 bedrooms needing something.
I appreciate Sonos is a fantastic, well-implemented system, and I'm sure if I bought one I'd feel the same as you guys, but it's the buying part that's putting me off. £80 for an ATV2 vs £230 for Connect (VAT free prices).
I think I may just wait and hope for ATV3. Lots of rumours about that it's going to be launched at the same time as iPad 3.