This. It's the FWB's and I's favorite position right now, so versatile and it gets both of us off with amazing grace. A few we've enjoyed lately: -Her laying on her stomach, with her ass thrust up a little and I'm on top taking her from behind. -If you've got a couch and a coffee table handy. Have her ride you, then she leans backwards, using the coffee table as support. She can then ride you and you've got perfect access to her clit and the view is great. -The bathroom counter. She sits on the counter, with her feet resting on the edge (knee's to chest). I'm a little too tall for the counter but you can use it, somewhat, as a fulcrum and get really deep. She can also move her legs around (IE: over your shoulders, wrapped around you, to the side, ect); also, perfect for a little clitty action. -The wall fuck. Pretty basic; she leans against the wall or uses it for support, kind of helps if you're similar heights though. And now I'm horny.
I like most any position and it depends on the person I'm doing. With FWB, I love doggy, and pretty much anything but standard missionary is great. My last boyfriend, was great at laying on the side, from behind.
Or, if you're broke, a couch cushion or any pillow-type thing that's got some resistance to it. Down pillows and such won't hold the shape. Personally I'm a fan of doggy. We're pretty different in heights though, so I've found that if I can put one leg on the floor and the other propped up on something (like a couch seat or box springs) it makes the alignment easier. Plus he can get a lot deeper. Win-win.