Depends if you will want to go off resort and explore, or if you simply want a nice hotel with all the stuff (and beach) in one place to just relax in. If the later, location is less important and it's more about the hotel/resort. On that basis just pick somewhere in Spain/Portugal with a nice all inclusive resort and don't pick a hotel that would attract 18 year old Brits. Greek islands are a good shout as well. So many...just pick one. Don't book during school holidays or the price can be 3-4 times higher.
Go on the main holiday sites like jet2, on the beach, trivago, tui etc. Also check expedia and places where you can do the flights and hotel separate as can be cheaper. Package holidays are appealing for the family goers but if it is just yourself, much easier to sort out booking things separately to save cash.