My rear surrounds are bookshelf speakers and are literally sitting on bookshelves. The shelves are about 40 inches behind the seating area. The speakers are at about a 45 degree angle to the prime listening area.
I post below a picture. You can see the black KEF iQ1s on the shelf.
What I am trying to determine is the optimal height. At present the bottom of the speaker is 65 inches from the floor and the bottom of the speaker about 26 inches higher than the listener's ear. This is a 5.1 setup. It sounds pretty good but but I wondered if it was too high. I tried a foot lower and it seemed too much "in-your-ear" but I am not sure of the ideal effect to shoot for.

http://img528.imageshack.us/img528/7445/sofaandbookshelsm.jpg (http://img528.imageshack.us/my.php?image=sofaandbookshelsm.jpg)

usually 2.5-3 ft above the listeners ears while seated.

Move the couch forward, it'll be fine.

There's no hard and fast rule in real rooms, despite Dolby's official spec.
For multichannel music, I defintiely prefer the surrounds at seated ear level. For movies, I now would rather have this, too, but I am less concerned, probably because I get wrapped up in the movie and don't pay attention to the surround effects as much.
You are comprised somewhat by having the side surrounds in the back, and comparatively close to the listening area at that. As you said, bringing them down makes it easier to localize. If you didn't like this, then it'd be best to leave them where they are. I have the same issue with my side surrounds and reluctantly, I've got them mounted about the same height as yours.
One thing to experiment with would be moving the surrounds to about 150 degrees from the center, that is, across from the opposite fronts. You might be too close to that one side wall though.