I'll agree with you on Daytona and Tampa.. but Siesta Key actually is a nice beach and a fun vacation spot.
As for expensive beaches in Florida- Key West, (already said) Palm Beach, Jupiter, Boca Raton, Miami...maybe even Naples or St Augustine, can all have an overall higher cost than WDW. Key West costs me about the same as WDW... it would be a lot more than WDW if I was comparing to most Disney resorts. Most of that is because of the transportation options, and activities that we do while there.. and mostly- I drink and eat a little (a lot) more while in KW.lol
Anyway.. I think all of these comparisons are odd. Not directing this just at you, it's the conversation. I don't understand why people continually compare WDW to other destinations. They aren't the same.
I can understand comparing Disney to Altlantis, or Legoland, or even Universal more so than to a "beach vacation". I do agree that there are "top vacation spots" to choose from during the decision making process.
Side note- currently I'm deciding between a kid's bday quick trip to WDW or staying in a Yurt and hiking for 3 nights. Apples to.....salmon, maybe? I have different motivations for each, and not sure which one I will choose. Either way it won't be because of Disney being good or bad. It may have a lot to do with crowds and Delta though. Lol