For me, one of the best feelings is giving someone a present, which they love. There is an old-fashioned belief that giving gifts is accompanied by more happiness than receiving them (I had to word that sentence soooo carefully, or it sounds soooooo wrong) but most of the people I know disagree.
I, however, stand firmly by that idea, because it is so beautiful to see a gift being well-appreciated and it adds more cred to my self-given title of 'Chief Present Buyer'. Plus, as someone who is hugely fussy, I tend to be disappointed by most surprises. Then there's all the present wrapping, all recycled naturally, card making and general excitement of giving the present. Buying a gift for someone comes with all the thrill of making a purchase for yourself but none of the guilt!
Still, I am willing to concede that there is little worse than struggling with finding someone a suitable present. You fight with the uncertainty of whether they will like it. Normally, your first instincts are right and if something jumps out at me as 'so xxxx' I buy it for them even if it's the wrong side of their birthday. Better in the long run, but annoying right now with a couple of presents still overdue after a day of shopping (somehow I managed to find a dress for somebody whose birthday is in over a month).
Then there's the fact that I can't wait for my impending birthday, because I saw the dress my friend has got for me but she won't hand it over...