I've been using Elixir strings for the past 10 years. I love them, and they really do last a long time. I have two guitars, one tuned to standard, and the other tuned to drop B. The standard guitar I keep 8s and 9s on, depending on my mood. However, on the B guitar, I get the thickest possible strings I can get.
If you haven't tried Elixirs, I'd recommend it at least once. They're really quality strings.
D'addario XL Nickel Wound .010s
I like them a lot.
What is it about Elixers that's so good? Tone? Feel?
Durability and longevity matched with quality tone. After a show with regular strings, you can usually hear the tone change because of the wear. With Elixirs you could play 2-3 shows before you'd hear any change in tone quality.
I remember back in the day there was some big deal about a special coating they have or something. I'm pretty ignorant about that kind of stuff, but the band I was in used to buy them for me from the band fund, so...