I hope it doesn't sound corny... but I've always wanted to play an RTS that has FPS elements. Like StarCraft, except you can enter one of your units and play as them.
I played a couple of those (they're quite rare) but they weren't executed very well, either as an RTS or as an FPS! My favorite...
We hardly ever get any decent coupons in the post, but there are some websites that can give you a small discount on online orders... if you're lucky :)