Yes, the first Hawaii cruise
DCL did was a round trip in May 2012 out of LA. It sold "well enough" for DCL to then add another cruise to the schedule for Oct 2012. Many people "jumped ship" from May to Oct, causing both cruises to not sell very well. On our cruise there were so few people that one of the dining rotations did not have a late seating. Meaning those CMs who were only serving early dinner (on that rotation) got less in gratuities. I felt bad about that.
We've also done a round trip Hawaii cruise on Princess (this past March). For that one, we only did one actual excursion (and it was an independent one, not DCL). The other islands we either just took The Bus (Waikiki) or rented cars.