The Panasonic XR series of receivers are quite good. And they do fulfill most of the requirements that you're looking for.
But they fail in the ease of use category.
A receiver that does fit these criteria
ease of setup, expected long life, and low price is all I'm after.
would be something like a Pioneer VSX-816K/S, or a VSX-1016TXV, or possibly a VSX-915/914 (I forget the exact last model # of the 900 series) if you can still find one.
As long as you make sure that a Pioneer receiver gets the ventilation it should have (which should be true of any receiver) there's no reason it won't last a good long time.
I've had more than a couple of Pioneers, and have known quite a few people that have had various Pioneers. Only problem they've ever had was from it being stuck in a tight enclosed space for too long and having somthing come de-soldered after a few years of being cooked.
Don't cook it and it'll be fine.
And the Pioneer's of the last few years have had an auto-setup feature. How easy is that? Just put the microphone in your listening position and strat the setup program. The 816 I mentioned has auto-setup/calibration/EQ.
Not to mention they're quite easy to use. I just had someone over this weekend commenting on how he's been loving his 912 because it sounds great, functions great, and is very easy to use.
The Pioneer I've got now I've been using for just over 6 years. And although I've not given it the ventilation the manual says you should (it says 8"+ of space on the top, I've got about 2") and have used it insanely heavily (probably well over 5,000 hours of use in the last 6 years) I've never once had a single problem with it. And every other Pioneer receiver I've ever seen in use has no problem lasting 5+ years (as long as the owner didn't cook it).
I see BestBuy has the VSX-816K for $250, and the 1016TXV for $399. I'd bet you could find better prices on those and wouldn't be surprised if you could find a 1016 for $300. The 816 would work well for you, but if you can find a 1016 for $300 then definitely go for that one.