I'd prefer this be set while John and Sherlock still live together. Sherlock has embarked on a sexual relationship with Molly, his first, and it turns out he's pretty loud in bed. I'd love to read a fic that alternates between what Sherlock and Molly are doing in bed (maybe a long, slow blowjob that has Sherlock writhing) and John's reaction to all the noise outside.
Sherlock/Molly + John