Oh we always go up Porlock Hill, we like to live dangerously!
The steam railway is good fun. We saw the Hogwarts Express but I don't know if it is still there.
Agree Tropiquaria is brill. They have a big adventure playground, puppet theatre, zoo, and two full-sized pirate galleons in a huge sandpit. The kids can dress up as pirates and just go mad while you relax with a cold drink!
I can thoroughly recommend Burrowhayes farm at West Luccombe if you want to go horse-riding.
In Minehead high street there is a pub called the 'Hairy dog'. It has the best play area of any pub I've ever seen, plus the food and service are good and it's not too expensive.
There is a nice little place at Allerford (near Porlock) that does falconry displays etc. They have a big barn full of all sorts of animals that the children are allowed to handle. I even held a baby meerkat!
Anyway, if I were to list all the great stuff in the area you wouldn't see anything of Butlins . Can you tell I'm a fan? We're going down there in August. We have stayed at Butlins before and thoroughly enjoyed it but this time funds only allow for camping. I'm sure you'll have a great time.