In a vacuum, this is an easy call to me. Dolphin wins hands down over any moderate. Better beds, better pool and much better location. The fact you can walk to two parks combined with the additional entertainment/restaurants of YC/BC and BWI is huge. At a moderate, you are a captive of that resort.
That said, I'm good at spending other people's cash. After factoring in the Dolphin's resort fee, I'm guessing your room rates at the two resorts are pretty similar. Then adding in the
free dining plan, magical express, etc., you are probably almost saving a grand by waiting a week and staying at CS. Although the location and quality of the Dolphin is much better, I don't think it's $1000 better.
The Epcot area can't be beat but for us the S/D aren't among choices for us since you can't have the dining plan, can't use magical express, and there aren't many rooms with balconies. We usually stay at the BWVs but this past trip and our upcoming Aug. trip we switched to the BCVs and will going to the YC in June.
I don't really agree with much of this since the dining plan and magical express are only a consideration for me if they offer a savings. For my six-night stay in July, my Dolphin reservation is about $1100 all-in (resort fee, taxes, etc.). For any other Epcot Deluxe, Disney is showing no lower than around $2500 all-in. Even if Disney offers up a 30% discount opportunity like last year, which is no guarantee, I'd still be saving around $650 by keeping my Dolphin reservation. I could probably arrange a roundtrip limo transfer through Mears and enjoy Flying Fish for dinner every night and still come out way ahead despite any potential saving from the dining plan or magical express.
As for Swan/Dolphin balconies, I've been extremely lucky. After about a dozen stays at the two resorts, I have only not gotten a balcony twice. I'm sure being gold and occasionally platinum with Starwood has helped quite a bit with that.