We started our relationship with audio books with the FANTASTIC Harry Potter audio books. I wish our school allowed Harry in the library, because I would love to use the audio books with my students. They are so well done.
This summer, we have been listening to some Percy Jackson in the library while we work, and we have been enjoying The Kane Chronicles (also by Rick Riordan) on audio in the car. Audio books are a great way to get through great material while doing other things at the same time.
The only downside I have noticed this summer is that the audio books during the day have replaced bedtime reading at night. That's not a trend I like, but it is easy to get lazy and let my son stay up later, playing, while I do something else rather than set aside the 30 minutes or so for our usual reading routine. But I know in my heart that that routine is precious. I just need to find the right material to restart our bedtime routine.
Now, I am on a quest through my book magazines for some new audio book titles to try. We started The Phantom Tollbooth read by David Hyde Pierce, and it's fantastic. I'd like to finish that one. If you have any recommendations, let me know!