I would suggest you look at one that is capable of that power, regardless of any of your findings, the worst thing you can do for your speaker is under drive it and to achieve reference volumes 100W/ch is at least the minimum I would look at and as others have previously stated, the chances of your system ever requiring all channels driven to the same volume level is extremely rare, if ever, and as you noted you will more than likely see each speaker at some point in a movie could require 100W to achieve refeernce levels, so having an amp that is capable of driving 100W/channle is a very good idea, too much power is a far better thing than too little.

My Denon 3808 is capable of 100W/ch. as shown here