I was in a very similar position. I was gifted the RX-V1400 and had to pick speakers. After much listening I know what speakers I want, but will have to wait a bit to afford them. While I am waiting I first tried a set of Peavey Studio monitors I own, even though I have a funny shaped room, the YPAO in the Yamaha set them up perfectly and the sound was just too sweet, unfortunatly they are not shielded and really made pretty colors on my TV

.
I then "upgraded" to a couple of small bookshelfs and a Bose cube I had laying around. Reset the system to drive a 6 ohm set, run YPAO again and another pretty good sounding setup. However that was only three speakers. Finally I decided to purchase an inexpensive 6.1 speaker set, the Onkyo 510 set from BB. Reset to 8 ohms, run YPAO, and sit back to enjoy a few flicks. While the Onkyos have no where near the dynamic range I want, having a matched set of speakers and a subwoofer all balanced by the Yamaha amp has given me a system I can listen too while I browse eBay in search of the perfect speaker set up.
Being able to move the speakers around and then just run YPAO to rebalance them is fantastic. I tried doing some tweeks to the setup that it gives, but found that I could not really improve on the experiance. I have yet to even begin discovering what this receiver is capable of. In addition to DTS and Dolby Digital, the PLIIx is very impressive, even TV movies sound great.
Enjoy,
-harry