Top or bottom double penetration

Wondering what the ideal double penetration would be? Lying on my back while the woman slides down my cock, then takes another guy in her ass? Wonderful, especially if she has a large chest, and I could feel her breasts squashed against my chest. I would also be able to see the expressions on her face as we pumped her, and watch her as she cums.

But I've always dreamed of squeezing my way into a woman's ass, and bringing up the rear, looking down the curve of her back, and watching my cock disappear in and out of her ass. But I've always read that the guy in the ass cums first, in a DP, and even though I can last quite a while, I tend to cum faster banging a woman doggie style or in her ass. SOmething about her buttocks slapping against my stomache ... sets me off.

Woe, to be in her ass during a DP ... but I'd want it to last, and I know I might cum too soon the first time. Oh, what to do ...?