Indeed doggy is a good way to enhance penetration and help stimulate your a-spot which is at the junction of your vagina and cervix.
We've also found that using the Liberator Wedge in the missionary position is very effective.
But - my wife's favorite is Cowgirl. Not only can she take me deep, she's in control of where and how the head of my erection stimulates her inside.
Experiment and enjoy!