I was just reading an article about how kids who consistantly eat dinner at the dining table, and kids who are allowed to serve themselves, are actually slimmer and that the learn to only eat until they are full.
My first child is due in June, but I think eating together as a family at the table is important. I think it's quality family time and is also a good opportunity to teach them proper etiquette (please, thank you, etc.). The findings make sense to me... I think it instills good eating habits. Children who eat their meals in front of the TV are probably more likely to grow into teens and adults who constantly snack while watching TV (or driving, etc.)
Ever since the baby got his high chair at 5.5 months we eat dinner as a family. Often, he screams and cries because he doesn't want to be in the high chair (he wants to be on the floor playing) but he will learn and this will be his normal.
We usually sit at the table but sometimes I let the kids spread out a blanket and have a picnic in the family room and watch a movie or TV. Those are usually the nights DH works late or if there's something really special on.
We eat at the table now...but this is a just reently started thing. I didn't have enough chairs for all of us (we only had 3 chairs, so we all ate together in the living room with the TV off) until 6 months or so ago. And they've always made their own plates...well, since they've been able to.
One of my boys is rail thin, one is average..both are 50lbs (7 and 5.5). My daughter is 16 months old and 20lbs.