We stayed at the Grosvenor in October (and at the Courtyard by Marriott last year). The Courtyard was a little nicer hotel, but we loved the Grosvenor's location much more. We were constantly walking over to Downtown Disney for evenings or breakfasts or shopping or whatever!
The Grosvenor is a little older, but it was very clean, the service was outstanding, the bars and restaurants were great, the pools and outside bar was nice and well-kept, and the Goofy/Pluto breakfasts were wonderful!
Deborah