My blanket answer is put is as much as you can afford in your front 3 speakers, then worry about the surrounds. If you are doing 5.1 the surrounds are more important. 7.1 or more then the side surrounds are more important than the rear surrounds.
This is a hobby where there is no amount you spend that theres not something that costs more and claims to be "better". Many go into debt, ruin relationships, or worse over the quest for the ultimate system. Most of my system I bought used and on average saved 50% or more off retail. All of it was demos from authorized dealers and had been replaced by "newer" models. In particular was the amps. While staying away from amplifier brands...I feel having more than enough power to drive the speakers is critical. Many speakers get damaged by not having enough power, much fewer are damaged by too much power to them. The amps control everything the speakers do. I mention this because it can impact how much you spend on speakers. This is even more important when considering certain brands of speakers...like B&W. They are power hungry to get the best sound from them.
I hope this helps in making your decision. I'm sure more info such as budget would help the forum guide you towards a decision.
Brian B replied to my question 2 pages ago which was basically the same question. At least the part regarding pm1's and what center.
I am in the same boat. Looking at PM1's. But was hoping for input on that as a choice for a all tv/movie setup.
An old friend of mine owns a shop that is a B&W diamond dealer and he recommend one speaker. Brian B gave some alternatives. I tried to multi quote across pages but it didn't work.
I would like to get more input on my question which is the same as yours.