Start with your guy sitting on the bench with his knees bent and legs slightly spread, leaning back with his arms outstretched and resting on the edge of the tub. Straddle him, facing forward, and lower yourself onto his penis, holding on to his shoulders for support. Keep your knees bent and feet flat as you move up and down or back and forth. The space between your torsos allows both of you to watch the action. There's also room for pelvic play, so you can maximize clitoral stimulation by rubbing your bliss button against his pubic bone as you gyrate. Take advantage of this you-on-top pose to titillate his pleasure-receptive nipples. Draw gentle circles around them with your fingers as you grind.