Who wouldn't want to receive clothes as presents? Truth of the matter is, clothes make for lovely gifts. They are practical, presentable (because they aren't exactly the cheapest to give!), and giving them shows you actually took time out to think.
Giving clothes to your friends is easy: a simple shirt goes a long way. A good measure for giving clothes to friends: you can give them something that you yourself want. More often than not, because you are friends and thus have a lot in common, they'd want the same thing.
Go general with your boss or colleague. A simple white shirt would be good, but grooming products would be a safer choice. The same goes with your dad or your girlfriend's father.
When wooing your mother-in-law with clothes, it's best go conversative. What's conservative? A nice cardigan is a good example.
And finally, for your lady. Girls appreciate clothes, period. As her beau, giving her lingerie is okay. But if she'll be opening gifts with her family, make sure she'll have something less kinky—like a nice dress or a cute shirt—from you. A final reminder: Please make sure you have her size right.