Europe 5* hotel with great kids facilities for 11yr old boy

[Tomboytown]

Water park or great kids club?
Canaries a bit too hot- maybe Balearics or France/Portugal

You could check out the kinder hotels in Croatia. I think there are three and they usually cater for families with children of all ages so should have stuff for an 11 yo.

(Sorry for all the “should haves” we’re going next year so I don’t know anything for certain just from recommendations.

Costa Navarino - surfing, water park good food

You might find this helpful. www.telegraph.co.uk/travel/family-holidays/europes-best-holiday-resorts-with-kids-clubs/
A couple of notes though: Even though it says that Pine Cliffs is good for great children, it still caters well for children up to age 13.
It highlights Club Med as being good for its circus skills courses, but Club Med also has so e good sports courses.