I have stayed at both the Yacht Club and the Beach Club, but haven't stayed at the Dolphin yet (I have ressies for Oct, though!). The BC is my second fave resort (Boardwalk is #1- awesome! But that's another thread...).
However, ithe BC might not cost you that much more than your govt. rate at the Dolphin anyway. Have you looked into getting an Annual Pass? If you will be there for 14 days it will already save you a lot of money in park admission (I think it pays for itself in 8 visits), and the hotel discounts you get with it are terrific!
I don't know what your Dolphin gov't rate is, but I remember when I was making AP ressies for Jan I was quoted around $180 standard room, $275 concierge (this is including tax) for the BC. The only bad thing is that you can only make AP ressies a few months ahead.
Now, I'm not sure about what I'm going to say, so please check this with someone else who knows, but I am under the impression that you can go ahead and make ressies now (or whenever it is CRO starts taking regular non-AP ressies) and when the AP rates are announced for your dates they will adjust your rate if you call. There is a little paperwork involved b/c they give you a new reservation #, and your deposit needs to be based on the original quote. But at least you would have your dates and rooms reserved.
Like I said, I'm headed to the Dolphin in the fall, and not super-exited about staying there. But, it's a short trip and the whole reason we are going is because we could get a great rate at the Dolphin through the Starwood program.
This is a trip you aren't going to be making again for a while, I say go for the magic... go for the Beach Club!
Nicole