We did all our Med excursions through
DCL as Castaway Club members. The thing that helped us with booking was to have saved the ones we wanted in our Wish List - that made selecting them easier. And being up at 2:50 a.m. for that 3 a.m. booking window to open! One thing we noticed was that DCL does save back slots for the 75-day window, and they added on extra times for a few excursions. Like the afternoon Pisa tour we were able to do which turned out to be one of our best excursions. We had booked the morning because that was what was available, but then I checked later on and found they had added an afternoon one.
Also people were able to get some excursions booked once on board as people changed their plans. I think what happens is that a lot of people go ahead and book through DCL to be sure to get something, and then if they end up working out something on their own as time draws nearer, then they cancel the DCL ones to do their own.
I haven't been on in quite a few days and I see that we may have some new cruisers to the group -- if I haven't added you to the list of cruisers in the first post of this thread, please PM me (or post here) so I can add you. School starts Monday so I am trying to catch up on a lot of things today and this is on my list