I agree with so many of the previous posts. DH and I are going to Disney alone, as a couple who does not have children. We are planning our vacation so that we can enjoy all of the fun Disney has to offer, while enjoying some "Grown up" activities too. We are going to make an ADR for the Cali Grill while there in August. If I had my choice, I would choose to have no children in the restaurant at all. That being said, we are at DISNEY and I think ANYONE going should get to the realization before they depart, that this is the world for children. You should not feel like you can't enjoy a nice night out with your husband because you have a child because of people like me, who prefer to go without. If I had a choice between a screaming/whining/yelling/crying child next to me, and one that is quietly entertaining themselves, regardless of how that is, I choose the child occupying themselves.
I hope that those that might be "bothered" by the glow of your son's DS get seated next to a family with 4 kids under the age of 5, and they'll show them what disruptive really is.
My advice (coming from someone without kids): Bring the DS with you, but don't assume that your son will need it to be entertained with it in order to behave. I agree with the other post that it might be nice to include him in the discussion about your day. I feel that if its not something you would want to include him in, that maybe the kids club might be the best place for him, but whatever YOU decide to do, I hope you enjoy your time, and don't worry, if you decide to go the DS route, the friendly people from Wisconsin that might be next to you won't pitch a fit.