The Seniors (1978)

This one starts with a chubby older guy with glasses and gray stubble just lying in bed, looking like he’s half-asleep. Then these two college girls—one blonde with long straight hair, the other a brunette—walk in and start teasing him. The blonde drops to her knees first, sucking his dick slow and deep while the brunette watches, playing with her tits. They switch it up, and the brunette rides him reverse cowgirl, bouncing hard while the blonde makes out with her. Camera gets right in there for close-ups of his cock sliding in and out, and the lighting’s warm, so you can see everything. Both girls are slim but not bony, with decent asses, and they take turns riding him until he cums on their tits at the end. Nothing fancy, just solid fucking with a mature guy who knows what he’s doing.