Select your speakers first.
Remember, the speakers determine the overall sound of the system, not the receiver.
The speakers you select will determine your amplifier needs. In a nutshell, efficient speakers can get by with less power and piggy speakers will require more power. Some speakers are easier to drive than others.
Once you choose your speakers, the receiver decision will pretty much fall into place. By worrying about the receiver first, you may well limit your speaker choices drasticaly.
Aaand, if music has any importance at ALL in this system. select your speakers using music, not movies. If a speaker can do music right, it will have no problem at all with movies. The opposite rarely holds true.