Craig, it was on my top 5 list as well, so when my wife and I were planning a Scandinavia trip we were sure to include it. IcelandAir has a great feature that lets you extend a stopover there for free, so we broke up the return trip to spend a couple days there.
Keflavik is the main airport; it's about a half-hour drive from Reykjavik itself, and an equal amount of time from the Blue Lagoon. We didn't rent a vehicle, as we were staying inside Reykjavik while there; IcelandAir also has shuttles from hotels to the airport, as well as to the Blue Lagoon.
I loved it (honestly, it's my ideal climate and for a while after I tried to convince my wife to move there) and definitely want to go back and see more of the country. I definitely recommend it. Thanks for the note!