I was checking our itinerary on the Delta website today and realized that despite what Expedia has told me, we did not have seat assignments for 3 of our 4 flights. I called and spoke to a very nice agent who said that the only seats I could book at this time were center seats which would mean none of us would be in the same row (the plane is pretty full already). I explained that this didnt work for me since I am traveling with 2 children. She told me that was a whole different situation and immediately booked us 3 seats together on all of our flights. She said that Delta has what they call family seating (in the rear of the aircraft, naturally) where they will rearrange other travelers to ensure that families are able to sit together. Personally, Im not crazy about sitting in the back of the plane, but Id rather be back there and sitting with both of my kids than up front with them in different rows! Just thought this might help someone else.