If you are looking to go down the PADI route as a qualified Open Water diver, i'm sure you are aware that it is split into two parts...... theory and practical.
My advice, wherever you decide to go, would be to do the theory before you go (e-learning with PADI) and do your assessable open water dives on holiday, that way you are not classroom bound sitting exams whilst on holiday.
As for destinations, I've only ever done 'live aboard' on the Red Sea so can't comment on resorts etc.
https://www.padi.com