I think a lot may depend on when you're going. Jenkel, I think you've made the right choice by going on a weekday when it's bound to be less busy as most children over 4 yo will be at school.
Also, the time you go is important. Our allotted time was 15:45 but people who go at the start of the day won't have the same problems that we had as there won't be anybody else already there.
As well as the website, the people on the ticketline also give the impression that you get 2-3 hours in Santaland. It's either a tissue of lies or they're badly informed!
My advice is, if the place is packed then just look for the things that have the shortest queues. In our case this was the film show, the bouncy castle and the merry-go-round. Actually the bouncy castle did have a queue but it moved very quickly.
The things that look best are the toboggan slide and the train. My ds wanted to go on these but even he agreed that it would take too long to queue and he didn't seem bothered once he'd been on the other things and seen Santa.
I'm not sure but the slide may be too hazardous for a 3 yo.
Hope this helps and I hope you all have a good time. Your children will enjoy it I'm sure.