With occasional exceptions I tend to go on my own mini-training camps usually somewhere set up to support training (http://www.pyreneesmultisport.com/ is my normal destination). That lets me train as I want but gives a lot of the basic support too.
I’ve done a camp with them which was good fun and also been on Epic Camp also good fun. In both cases the level of support was very high and whilst training was set out there were options to tailor it (add on more).
From your points:
Cozy appartment - I’m there to train I don’t need luxury and don’t really want to spend money for it.
Set plan, thinking is too much effort. However good if there’s some flexiblity. Options to add in more, ride for longer etc. Maybe depending on abilities.
Weather should be warm and sunny!
Countryside should be pleasant, but it’s not essential as long as we’re out of big cities and there’s good roads to train on.
Professional coach - not essential to me, but no problem if there is one.
Groups meeting your ability - definitely need to have people to work with and push you.
Just relax in the time off - any screenings etc should be optional.
Catered food! I’m a lazy cook, eat better if someone else does it.
I’d say to me the most important stuff is - decent but basic living facilities, good weather and training environment, good support with food etc and a decent group to train with.