Hi there - After trying different deluxe resorts at Disney, we've vowed to only stay at YC or BC. As far as concierge - we've done both. And, we've done regular rooms as well.
The resorts are very similar as far as level of service and concierge food offerings. I didn't notice any "noticeable" difference. As far as room views, and I'm not talking specially about concierge, the BC has some full balcony rooms and some standing room only tiny balconies. We always request a full balcony because we spend a lot of time relaxing out there during our vacations. I do believe all Yacht Club rooms have full balconies. So be careful if you choose Beach Club and want a full balcony.
The Beach Club is a bit more casual and it's closer to World Showcase. That's why I'll have to say it's our pick between the two. However, we love the Yacht Club. You know, you get the same big advantages with both....Stormalong Bay, walking distance to Epcot and MGM or the Friendship, the boardwalk right outside your door, and great service. We've never had a problem with any Cast Member or the services at YC/BC. The rooms are the same size with the exception of the Beach Club...I think there are dormer rooms that are a tad smaller than the standard room. Again, simply request that you DON'T get a dormer room. We've always had our room requests fulfilled.
Either way - you'll have a blast. I'll be at BC 12/8 - 12/13!!!
PamNC