DD2 will be 3 in Feb and she sits in a variety of places. lol She can sit in a booster chair and eat, and that works if we are all sitting down together with a fairly clean meal. But for lunches and things she tends to wander off and forget she was eating. And for those kind of meals she usually just eats in a regular chair, but sometimes I will put her in her high chair so she has no choice but to stay put and eat until she is finished. I also put her in it if we have spaghetti or something messy like that, because she is a wiggler and she gets a lot more on her lap in the booster seat.
So... whatever works for you.