Having been to both of these places, I can definitively answer this question for you. It's Honolulu.

Unfortunately, it's looking like I'll have the opportunity to go to one or the other but not both at the end of October. The Kazakhstan maintenance trip conflicts with the IEEE Nuclear Science Symposium conference. I'm going to have to go with Hawai'i on this one, which is a bummer because I really enjoyed my time in Aktau last time. But, alas, the maintenance trips to Aktau are a recurring thing; the opportunity to take Glenn Knoll's short course on detector physics at IEEE is not necessarily available forever. Plus, the papers I'm on for this conference represent the most interesting thing I'm currently working on and the segment of my work which I think has the most potential to grow into a career-basis project. That, and I'm rather taken by the idea of snorkeling.