I use multiple reward sites so I can make sure I'm getting the best deal. If the deals are similar, I just go with the one that I'm closest to reward on.
One of my favorites is Ebates. Ebates is a cash back program, that also lists coupons, so your savings are easy to see.
For a limited time, Ebates will give you $5 just for signing up. Joining is free and you don't end up with a whole bunch of Spam like some sites. I'm sure most of you are done shopping for the holidays, but if you're sending any last minute flowers or gifts, make sure you're using a cash back program.
If you're still not sure, why not sign up to get the $5 and then take a look around the site. If you join, I'll also get $5! It's free money, and free money is a wicked lovely thing!