I have just come back from this lovely trip. Be prepared for rain and heat. You can pay for the premium upgrade seats but you cannot book an exact seat. It depends who you fly with as to the cost and what you get for your money. I booked Thomas Cook and all you got was a bit o extra roomand free drinks during flight. My advice is get to the airport very very early 4 - 5 hours in advance and be first in the queue for economy seats and then ask for an exit seat as these do not cost any extra money. Legroom on Thomas Cook flights are not brilliant though. You book the premimum through your travel agent that you booked with, ours cost about £175 each return.
I think that you have to contact the airline regarding premium seats but not too sure as ive never booked them.
You can book a premium grade seat, but cannot choose your actual seat number. You book your seat upgrade via Ocean Village, not via the airline (unless it has changed since last year).
Many thanks, any ideas as to best beaches.
Many thanks for all your comments - any ideas on the best beaches anyone please.