I waited 34 years to meet Mickey Mouse and I did in September ! My parents couldn't afford it when I was growing up (Florida) so I am glad Paris gave me the opportunity !
My DD's aged 5 and 10 loved it and we did go in term time (first time I have done this) and it was quiet and perfect holiday).
They did agree though that I had the best time out of all of us (Hubby said I looked happier meeting Mickey than I did on my wedding day) !!!
We have also done Centerparcs 4 times and those were when the kids were younger so no school issues for going in term time.
We do the walks and activities but the pennies do add up ! However seeing the girls with falcons and baby foxes and all sorts of other animals/bugs (I have tomboys) was brilliant.
We have only visited the Whinfell and also have done it as a couple with friends and we really enjoy it.
I haven't heard of Bestival but I am going to google it !!!
This year we are doing caravan park as the girls love this but it also is quite expensive for a site with lots of facilities.
I don't think your children will think you are tight, I never had a problem with my parents not taking me to the places I would have liked as I have been able to experience them with my children which was great.
Some of the best days we have had out have been picnics to the park, frisbee etc, or setting off in the car to larger parks with swings etc.
Kids will enjoy anything really, and although we do have holidays, I know they would be just as happy with time at the beach. The most important thing really is being together as a family x