I've been to the Melting Pot in Bellevue twice now and it is really in a class by itself. It turns dining out back into an event, not just a stop along the way. The best way to experience this place is to order one of the 3 or 4 course meals, although stopping by for dessert and drinks could be fun too. I loved the cheese fondue, served the classic way with all the fancy ingredients you skip on when you make fondue at home. The dinner portion is crazy--they bring you a tray of raw food that you skewer and cook in the broth of your choosing. We've splurged for the Coq Au Vin and it is much better than just the plain broth or oil. The big finish is, of course, the chocolate fondue and you can have it several different ways. The Bailey's Irish Cream fondue was particularly good.
They do have a vegetarian option that has ravioli, veggies, tofu, etc. However, everyone cooks in the same pot, so if you go with carnivores, be prepared to watch your tofu simmer with their steak. I usually get sick from meat, but dipped my veggies in with the meat here and felt just fine afterward.
The price is pretty steep, with the 4-course meals running upwards of $60 per person, but you'd pay as much at any other nice restaurant for that many courses. What seems really luxurious is the amount of time you get to spend over dinner here. For us, it was easily over 2 hours, which gives you time to have nice long conversations over dinner. So make sure you go with people who's company you enjoy ;)