We absolutely love "window fucking" in many variations! It's intensely erotic to set up a situation where random voyeurs can get an eyeful. We have two favorite hotels, made for window-fuck scenarios; one is a Marriott with a club floor section that occupies the 7th, 8th, and 9th floors of the tower, the other is a "no-tell motel" on the edge of town.
The Marriott suites are up high enough that you can make out some of the detail in the suite's windows from the parking area. KK loves being naked, pressed up against the glass, and fucked from behind, in full view, as she says, "Of God and everybody..." The no-tell motel venue is hot for different reasons; it's an old school, 60's era drive-up motel. You can open the drapes as wide, or as little as desired, and fuck in full view of anyone who happens to walk by. I often sit in the car, watching KK fucking a lover through the plate glass window.
On the DP topic, dildos are a great way to experiment with both traditional vaginal-anal DP, double-anal (if she's really adventurous), or the absolute ultimate, best kind, DVP - two cocks in one tight pussy. KK love's DP and DVP - we're well beyond the simulated stage. There were role-playing situations, most of the time in the bathroom, sometimes at hotels that had good mirrors, where we used two suction-cup base realistic dildos for KK's ass and pussy, while she sucked me, simulating the "air-tight" scenario.... incredibly hot.