When those are the choices, seeing her spread for him and getting fucked.
But the thing I like the to see the most is the seducing and flirting by them ending up in him touching her. First time I saw this, we invited a guy for a threesome and met him in a coffee bar to meet him and see if there was a click. Once she gave me the signal he was ok, I went for paying the bill and when I returned I could see under the table where she had spread a bit and he was cuddling her panties, looked so hot to me.