I would suggest Tenerife or Calpe (Southern Spain). If you go to Calpe over the winter, you will almost certainly bump into a bunch of World Tour riders as many teams use it. Remco has a place there and owns (I believe) a cafe.
I’d never heard of it until I went on a Cycling Camp a couple of years ago - now it is my number 1 choice.
Tenerife is great if you want a high proportion of climbing miles - it is hard to find any flat routes, so recovery days can be a challenge.