Oh, it’s different for everybody. But a lot of asexuals frequently bemoan the lack of someone to cuddle with. Cuddles and hugs and even kissing might be quite normal. Co-sleeping—well, sometimes it’s even sort of nice to share a bed with a friend, isn’t it? Sleeping with somebody (in the sense of another person being present) is such a comforting, bonding thing. So sharing a bed could definitely be a thing.
Certainly I think significant, intimate physical contact is pretty typical, though not universal. Touching each other in the ways you don’t normally touch somebody who is just a friend—the things that if you tried them with someone else, might give them the mistaken impression of sexual interest, but is safe with family or close loved ones.
There’s a gender behavior thing here, though. Most women (in the West, anyway) grow up with the norm of close physical contact with other women (and men they’re close to) being okay. A woman doesn’t need to be in a committed relationship with another woman in order to snuggle up on the sofa. Most men, however, are socialized against that kind of physical contact with anybody but someone they’re in an intimate relationship with. By no means all men, of course; some men are very cuddly! But John, for one, certainly seems to have bought into this big-time.
So I don’t know if John would be much of a cuddler (which is a crying shame, because he’s like an adorable plushie with tragic eyebags and an angry glare that somehow just makes him cuter).
For that matter, Sherlock’s more casual about physical contact, but he doesn’t really seem like the snuggly type either, does he?
Still, that one moment from Emma’s Cure for Boredom persistently sticks with me, when John presses his socked feet against Sherlock’s thigh and Sherlock wraps his hand around his toes. That’s the kind of intimacy that’s utterly non-sexual and yet not something you would be likely to do with anybody you weren’t in a relationship with.
(That bit when they’re drunk and John presses his sock feet to Sherlock’s chair. Just kill me now. You have no idea how badly I wanted Sherlock to just reach down… Or, well, probably you do.)
There’s another story that tragically was taken down, because it’s perhaps the single best example of physical contact used for UST that I’ve ever seen. In it, Sherlock and John were so casually intimate with each other, doing things like casually helping themselves to each other’s pockets. There’s one bit where Sherlock’s got his bare feet propped up on the arm of John’s chair, and John runs a finger down the sole of his foot. It reads at once practically unthinking and blazingly intimate, because you would just never do that with someone you weren’t extremely close to.