First of all, a shoutout to the wonderful crew of the Oasis of the Seas. You are magnificent, providing excellent service and always smiling under the mask, that you are unfortunately forced to wear even outside on deck.
Embarkation started off a bit chaotic, as nobody knew where to queue for their time slot. But that was cleared up by RCL's port personnel pretty quickly and they started to sort people into the correct queues, which vastly improved efficiency at that point.
The cruise on the Oasis was wonderful. The ship is in excellent condition, with well cared for (real!) plants in Central Park, and more than enough sunchairs on deck. I especially enjoyed the Solarium, an adult only area in the front of the ship.
The cabin was large and spacious, with a big porthole to look outside.
There is more than enough storage and closet space for even the most enthusiastic pack rat.
The only issues that I had were that the bed and pillows were much too firm (and the pillows were too high), which made sleeping a bit uncomfortable. Also, the sound insulation to the neighboring cabins could be better, you can hear the toilet flushing in adjacent cabins. Furthermore, the cabin doors are so heavy that they slam closed very noisily...
Awesome snorkeling AND the drink package works on shore!
St Maartin is a great island. The town is nice, with some old, narrow shopping streets.
There is a water taxi that takes you into town from the cruise port for 7 bucks round trip.
Taxis are available; however, they are fairly pricy, at least for single riders.
We were told not to visit the French side, as they have some political unrest over there...
St. Thomas is a port where you can almost stay on the ship. I did an excursion, but got left behind with some others of my group as the driver left 20 mins early from the second stop. The town is nothing special. If anything, I might do the skyride the next time and that's it.