Yes, we are in a concierge room on the 6th floor. I would think the noise could only get worse on the lower floors, though - so ask to be somewhere other than the front of the hotel if your DS is a light sleeper for sure!
As far as concierge - I don't know if I'd pay an extra $200 a night for it. We paid $100 a night and it's worth it to us. The breakfast is fruit, bagels, pastries and breads, cereal, and beverages. We have been eating breakfast there in the mornings and then bringing some extras with us for mid-morning snacks in the park. The lounge is also good for an afternoon snack (they have tea from 11-4 I believe with little tea sandwiches and pastries, cookies, chocolate covered strawberries, goldfish crackers, snack mix and beverages). From 5-7 they have cheese and crackers, veggies and dip, assorted fruit, and a hot appetizer. (Yesterday it was chicken teriyaki skewers.) So you could make dinner out of it. In the evenings (8-10 I think) they have several desserts (pastries, chocolate covered strawberries) and milk and cookies. At 8:15 they have storytelling for the kiddos - it's very cute. They put pillows and blankets on the floor and the storytellers are great with the kids. Some nights they also have "Songs from the Hearth" with a person playing guitar and I guess singing. There is a great view of the fireworks from the lounge & balcony and they pipe in the music from the show. In the lounge there are tons of games and puzzles, a TV and couches, coloring pages and crayons, a computer and printer, etc. You can also borrow DVDs to bring to your room. There is some sort of craft time for kids but we haven't been since it was mid-morning when we were in the parks.
It is the little things I like - being able to get a bottle of Perrier (which they don't have in the lounge but fetched from room service just because I asked) and not having to walk downstairs and pay $4 for it, for example. Also in the 6th floor lobby there are two people at the concierge desk to help with whatever you need anytime. The woman at the desk last night noticed my DD6's Tink nightgown and 30 minutes later stopped us in the hallway and told my DD that Tinkerbell had left a delivery for her. It was a signed photo.
When you are booking, are you getting a concierge room or are you adding concierge on to another room? I think if you try to add it on, then (a) you may not be on the 6th level; and (b) it costs more ($175 a night I believe). When I made the reservation, concierge rooms were sold out, so I just kept checking back and eventually one came open so I grabbed it and canceled the old reservation.
Hope that helps some! I'd be happy to answer any other ??s.