My husband for the most part will sit and watch us, stoking his cock while we play. He will if asked (and I do) massage my feet when I"m getting fucked. The sensation for me is immediate I cum hard when my feet are being massaged and I"m getting fucked.
There is some fun banter between us sometimes my bull will look over at him and say, "look how your wife loves my big cock". Or if I"m sucking hims he'll tell my husband that I"m the best cocksucker he's ever had. It's all in good fun...
Of course hubby does his cleanup once my bull deposits his cum in/on me a major turn on for all three of us.