I fly around 200K miles per year, and United is my #1 choice. I love UA . After UA, if the times/routes don't work out, then I try to fly Alaska/Delta/American (and credit to Alaska). And after that, I fly VX... VX really does have the best coach product. So for the flier who doesn't fly enough to hit Premier, then I would recommend flying VX. And yes... I said Premier. I think Economy Plus makes United worth it over VX, actually. The "experience" in Virgin American may be better, but if you just want to bring your own laptop / entertainment and have some legroom, then economy plus really is key.

Now all that being said, if you don't fly enough to make 25,000 miles per year on a carrier, then I would probably fly strictly on fare anyways... i.e. don't limit yourself and just take the cheapest / best route you can find.

Anyhow, those are just my thoughts. I really do like flying VX, though.