I.M.
Hi, sounds like you got lots of recommendations on the seats, but part of the problem could also be that facing backwards is really boring. I'd second the recommendation for toys or other things to hang from the seat. My son likes this adjustable activity arch from Tiny Love that I bought, which fits onto almost anything, and doesn't require hanging onto a car seat handle.
Here is a link to it on Amazon, though there are other things like it.
http://www.amazon.com/Tiny-Love-Sunny-Stroll-Yellow/dp/B0...