D.B.
We thought we could make it through my son's entire childhood without ever having a bday party at Chuck Cheese, but he's asked for his 5th birthday there. I think Chuck Cheese is one of the worst places for germs and what not, but its his request, so I'm relenting. LOL
I just booked my party on line and if you have your party on a Sunday you get an extra 100 tokens free, plus 20 tokens free for booking it on line (you can still go in to the actual location to pay your $30 deposit instead of putting your credit card info on line). You will get the tokens on the day of the party. Also, its $10.99 per child for the basic party package, which includes 16 tokens per kid, 2 slices of pizza per kid, unlimited drinks and 90 minutes of a secluded (as secluded as it can be) party area. There are also some additional extras that you get, such as a dedicated party person to help you out. You will still need to order pizza for the adults, but I would wait to do that the day of so you know how much you'll need. There are also several perks that the birthday boy will get with the basic pkg, including a bank with addtl tokens for him, a blow up birthday crown with 8 tokens build right in, time with Chucky, etc.
I would say your better off going with the party package on the weekend, because if not, you won't have enough seating for all of your guests and will also have very limited time frame (I think less than one hour on weekends) to enjoy yourselves. As for the cake/ice cream, your better off bringing your own IMO. Their cake and ice cream is very expensive and very plain looking (and in my experience, not very tasty).
Check out Chuck Cheese on line for all the info, but it seemed pretty reassonable to me, especially since the mess will be THERE and you really don't have to do much yourself.
Hope you, your guests and your little guy have a GREAT time!