Short break at Christmas

[Caulidop]

I was thinking of taking the kids away around Christmas, for 2-3 nights. I thought it might be nice to go abroad to somewhere slightly warmer, but not set on that, just want somewhere we can all have a nice time. Any suggestions? Kids are 7 and 11. I have looked at some recommended (elsewhere) UK hotels and came across some insane prices (insane to me is £500+ per night). Particularly keen to hear if you've done or doing similar. We'd be looking at between Christmas and New Year, not over those dates.

Slightly warmer would mean southern Spain or Canaries and I don't think that makes it worthwhile for 2-3 nights.
A lot of resorts and attractions will also be still closed and there isn't a lot to do
And I doubt it will be cheap.

I would look for a place in the UK with plenty of indoor things to do and a family room.

I heard some people recommending Amsterdam though, it seems there is some festival after Christmas but it will be cold and could be damp.

Morocco? But that's a long way for 2-3 nights!