The Marantz is a much better choice for MA's than Yamaha. Either the 7500 or 8500 will work fine as both have a nice, slightly warm sound that matches perfectly with MA. The Marantz line from the 5400 or new 5500 have far more multichannel power than Yamaha as they use better power supplies. There is no downside to the Marantz/MA combo at all. You just need to decide how much you want to spend. IMO the 7500 would be just fine. The 7500 is at the same price point as the 2500 and while both are good units the Marantz is better for MA's and a better unit overall, especially for music. If you are looking for an alternative to Marantz for MA's forget Yamaha and consider the Elite line. My Elite and MA's are great together. If not get the Marantz and you'll be happy.
Features should definitely take a second place to sound quality. The general consensus on Yamaha I feel is that they are great for a bright home theatre receiver and not so good for music.
I think elitefan is trying to say the Monitor series may not be a good match with a Yamaha because it may be too bright a match. You should listen to the Yamaha with the Monitors and see if you like the sound. Also keep in mind that Yamaha rates their receivers a little high, 100W should be taken as 70-80, and the 130W of the 2500 should be taken as 100 when comparing it to Marantz or HK who give true wattage ratings.
The YPOA is the same thing as Harman Kardon's EZset feature. While it's sufficiently accurate when moving your gear around to where you like it, it will not be as good as using an SPL meter to calibrate your speakers.
I'm not sure if Marantz uses an automatic speaker adjuster, but it's nothing to base a purchase on in my opinion.
I agree with therealelitefan, the Marantz is definitely the better choice for those speakers.
I just looked at the Marantz website and the new 7500 has MRAC or Marantz Room Acoustic Calibration. It seems everyone has jumped on this bandwatgon and I agre with Kano that the best and most accurate way to setup a receiver is to use the on screen menu and a SPL. I have read several receiver reviews and most of the auto setup systems make errors, even very expensive units like the Yamaha RX-Z9 are not perfect by any means. Anyone with a good system should have a meter anyway. Allan, I suggest you take a look at dynaco.com and check out their Elite prices on the vsx54 and 56. Mighty tempting.