Mayfield Country Club, a course w/ little architectural merit in western KY, has the ultimate in adjacent tee boxes. Three holes (4, 8, 18) share a single tee box. And it's not especially large.
Holston Hills has a couple of tee boxes (12 & 18) that are close together but not quite adjacent. These work fine. Rather sociable & I think better than trying to hide the tee next door. You're better off knowing if the guy on the tee next door has a Nike driver out.