Having worked at Sesame Place for a stretch of time when Disney was attempting to purchase the Muppet characters and properties, I can tell you first hand that there was an attempt by Disney to "take over" the marketing of the Sesame Street Characters. CTW or Sesame Workshop (as it is now known) is strictly involved in creating the programming you see on TV and video. They liscence all the merchandising to outside companies. When Busch Entertainment began to have financial troubles Disney made a strong push to buy out Sesame Place and the theme park rights to the characters, this was long after MGM stopped being a "working studio" so the change from NY street to Sesame Street was still feasable. However, when Busch Entertainment was bought out, Sesame Place was the lynch pin in the deal, if they had sold that single entity to Disney the deal would have fallen through.
Disney did consider buying Busch Entertainment as a whole, but decided buying all the extra properties just to get Sesame Place was not worth it in the long run.