One of the very best ways to masturbate is between a woman's breasts. My wife has average size breasts but she has learned how to fold them around my erect cock. We both enjoy watching as I slide in and out between her breasts. This can go on for a long time if you like, or you can cum in just a few minutes. She enjoys the sight and smell of semen shooting onto her chest and neck. Sometimes we do this in the morning and she 'wears it' to work.
Try this. I promise you it is one of the most erotic things you can do.