In my opinion, important features to consider:
5.1, 7.1 or more--how many speakers do you want to run? Even if you only have 5 speakers and a sub in your main room, you might still want a 7.1 because they have the capability to run a second pair of stereo speakers elsewhere in the home.
Networking--all by the most basic models these days have networking built-in. However, most do not have wi-fi built-in so you have to hook them up via ethernet cable or buy an adapter. Networking gets you (i) direct access to streaming services (pandora, etc.), (ii) Airplay and the ability to play files from your computers, (iii) control apps for apple and android phones/tablets, and (iv) easy firmware updates.
Room correction--software that adjusts the frequency curve for each speaker to try to adjust for your acoustic conditions. It uses a little microphone to do this. Many mfgrs use Audyssey; others (like Yamaha) use their own. Audyssey seems to be the leader.
HDMI standby pass-through--a lot of people like this. It gives you the ability to watch TV or a movie without turning on the receiver. Good for sleeping babies, nighttime viewing, etc., where you just want to listen through the TV's speakers. With your PJ though you might not care.
HDMI conversion--ability to take, e.g., component video (from an older DVD player, a Wii, etc.) and output it via the HDMI cable along with your other HDMI sources. Otherwise they just pass the video in whatever form it was sent and you have to run several sets of cables to your projector/TV.
Budget--how much are you willing to spend? If you have $1000 to spend, you'll get everything you need--just take your pick of the 2013 models. If you want to limit it to $300 or $500, then you'll have to make some choices.