I am very surprised that no one mentioned the User Experience Professionals' Association (UXPA) conference. I always make a point to attend because they are practitioner-oriented (as opposed to academic). UXPA will host two conferences in 2013 (Washington DC and Shanghai). http://www.usabilityprofessionals.org/uxpa/tag/2013/
ACM SIGCHI has a more academic conference, but the advantage is that you can learn about developing tech and research. There is also a UX track with some practitioner-oriented papers and presentations. It's a fun conference, but there is less bang for your buck... especially since CHI 2013 is in Paris (and you would be a tourist like me)!
The IA Summit would be my 2nd choice next to UXPA, though I personally have not attended the conference. I have been very impressed by quality of the talks (I have listened to a few recorded ones).
I have also considered the IxDA Conference as well, but I have not attended.
(Note: This was my recent answer to a closed question, which was reported as a duplicate to this one. I edited the answer a bit before posting here.)