Diamond, you've gotten a lot of good advice from these fellas. I can't really add to it except for to give some personal experience. I took the plunge on internet brands mentioned around here and tried SVS for my sub and Emotiva for an amp. SVS has exceptional customer service, and Emotiva certainly has above average service. I have a friend who bought Aperion speakers and loved them, so I recommended them to Gimpy Ric (a member here), and he seems quite pleased with them as well.
It's true what they've been saying...speaker preference is very subjective, so you need to audition. One thing, though, is that you'll want to make sure that your dad likes them. Tough for a holiday present, no doubt, but he might not like exactly the same sound as you. My advice would be to narrow down the list of candidates and then order some near the holiday. That way, you've got a nice gift for him, you can set it all up for him, and if he doesn't like it, you can still send it back. Aperion has a 30-day no-risk trial (so you pay nothing, not even shipping) on their systems, and AV123 has the same deal on their bookshelves. You can check with the other companies, as some will make you pay shipping if you return things (which is actually quite fair). It's not important to match the speakers to the sub in terms of companies, so you can mix and match. For aethetics, though, it may be best to stick with a set from one place.
Anyway, happy hunting!