Sorry, but I don't think it's worth it, either. The sundaes are good, but the food is nothing special. My DH and I decided we would no longer make lunch/dinner reservations there - too pricey for what you get. If you're going for something like the Kitchen Sink or something, sure, but not for the burgers.
If you do go anyway, my DH and I have enjoyed the Milky Way sundae, the No Way Jose, and there's an Oreo sundae I liked (don't know the name, though). I think Ghirardelli sundaes are just as good (but we can get those in Chicago anytime). This trip, if we go for ice cream, it will be to Ample Hills Creamery at the Boardwalk.