As married man with two kids, I always found it unfair the way some of my employers gave me benefits over some of my single co-workers. If I asked to have a day off to go on a field trip with my kids, I'd get approval without little trouble. A single person asking to have a Friday off since friends were coming into town would generally get a refusal.
Don't know about others, but I don't ask for time off. I tell them that I'm taking time off.
I've never had it refused (without *good* reason), and if they did refuse once, they wouldn't get a chance to refuse again.