My wife is about 100kg and 4'11. She's never had sex with anyone before me and it shows. She used to just kind of lay there, legs not open or anything. But gradually she got the idea. We're using the wedge cushion method like everyone's suggesting, but we lay a towel on top of that because her vag is like a constantly-running faucet. Doggy is nice. Her ass is really big but also really soft so it's easy to spread apart and get deeper. I'm 6'2 so I'm tall enough to grab her face and kiss her while I'm hitting it from the back. However, since she's so short, it's kind of awkward to reach so our favorite is missionary. We start slow, me kind of hovering over her, taking her all in. At this point I usually suck on her tits. Then, I usually wrap my arms underneath her and hug her. Sometimes I hold her face while tongue-kissing her. I love it when she grabs my hips and squeezes, basically telling me "go deeper." The absolute best is pinning her legs even further back and hitting her cervix, that airpod-feeling thing at the back of her pussy. It drives her insane. She usually talks with a deep husky milf voice but when I speed up, she moans like a fucking hentai character.
Sorry for the essay. TL;DR, missionary sex with my wife is my favorite thing in the world.
Don't get me started on cowgirl, 69ing, and eating her out