Ok, a bit of feedback. Done both Santa Special at SVR and also the Snowdome. The Snowdome wins without question and we'll definitely be going there again next year.
Whilst my toddler enjoyed the train ride at SVR, thats all it was really, a train ride. No effort had been made to decorate the inside of the train, no entertainment provided for the kids along the journey, it was just the normal journey which you can do at any time of the year. Once we arrived at Arley we all disembarked to be ushered into a marquee with a 45 minute queue to see Santa for 5 minutes and receive a gift. The only entertainment in the queue was a brass band, who only occasionally played. Conclusion...save your money, not at all magical.
The Snowdome in comparison was far superior. At the beginning you're greeted by a toy soldier on stilts who prepares the kids (and adults) for whats in store. From here the solider opens the doors to a beautifully decorated snow zone where the kids can sledge, ice skate have snowball fights and generally run around like lunatics. Next, at the sound of the trumpet, they all go into the theatre to be entertained by a 20 minute performance with Santa and his helpers. And then finally they're through to Santa's house where there are lots of immaculately clean and well groomed animals including donkeys, rabbits, goats, ducks, and of course Reindeer. Alas there is no sign of Santa again, which is something they could address in future years, perhaps they could have one, aherm..him wondering around handing out small gifts occasionally. But the kids do get a small gift when they leave, although I'm not sure if this matters as the kids have had such a magical time up until this point I doubt they're too bothered.
As already mentioned, the Snowdome provided the experience we were after and at roughly the same price as the SVR IMO is much better value for money. And no, I dont work for the Snowdome! :)
HTH