I feel a little strange offering advice since I'm a guy but, well, I've heard some excellent advice from sex therapists and so I'll pass it on. This may be useless. You'll have to decide for yourself.
I've heard many women need to find the right position to achieve clitoral stimulation during intercourse. They recommend communicating the problem with your partner and asking to play a little game in which you guide him.
If he's on top, grab his hips and move him around. Try changing your leg position to adjust the position of your pelvis. Try pulling him "up" a little so the penis is entering from a higher position. I'm told many women don't get much out of large thrusts so try pulling him deep inside and keeping him there so the two of you can more easily grind against each other. My wife particularly likes this approach as she then also gets to use her muscles to squeeze and generally drive me wild. Another bonus is that guys wont orgasm as quickly this way. Being on top is also a common cure for a lack of stimulation as you have more control of where contact is made.
So that's what I've learned and these techniques work for my wife.
There, now I'm embarrassed so I'll walk away.
Cyran0