Any type of new seat might be so "cool" he will be happy to sit in it. A booster seat should do the trick. Still, he might not want to be strapped in. My 2 year old has never liked to be strapped into anything. He only likes the stroller if it is moving, if not he whines and cries to get out and move. Anyway, with meal time we get him to sit at the table for a while, but then we let him get up when he wants. Otherwise, we spend meal time fighting with him and not getting to eat or talk. We just put the baby gate up so he can't leave the kitchen. This has worked for us and he is getting better. He sits at the table about half the time. As he gets older and can better understand I will enforce table manners. His 3 year brother has to eat his food before he can play. Good luck.