There is an official meets thread now, I can't link it since I am on my phone but you should be able to find the link in the links page.
I always like to go to the spa on sea days since pet days are always a little more hectic. The activities on the ship vary from cruise to cruise so unfortunately there is no way to know when you should book any spa services, just take your best guess. if you see a must do activity you can always try and reschedule.
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