For something really intimate, I love if he sits up (on the couch works best) and then I... basically just sit on him. I can sit on my knees and hug him and it's really easy to move.

For something less intimate, we like to start with 'reverse cowgirl' and then I lay down with my head by his feet. I can support myself with my arms to help with the motion... and he can also hold my hips and help me thrust.