if your post office has quick return they can scan it and gamefly will instantly know that you have mailed it out and ship you your next game. a lot of post offices just dont because they dont have it, are to lazy or busy. try taking it into your post office yourself.
for rpgs i would get dragon age 2 or mass effect 2 there both great games. action adventure id have to say assassins creed brotherhood, and little big planet 2 is really a creative game, but has some things that are hard to get at first if you have never played LBP