We (self and husband-50s, and daughter-22) are sailing on Radiance on 5/24 as well. We're in a C-category suite, deck 10 I think, not aft but within a few cabins. We'd be interested in hearing from others traveling with young adults.
I've done a good deal of research on this ship (have only cruised once on RCL, a 3-night Bahamas on Sovereign), and it sounds fabulous! I'd love to hear more about the ship, especially the Alaska itinerary.