first of all, thanks so much for the responses! this is my first time using this forum and i'm loving it.
i did think that, perhaps, many of RS travelers might not use marriott-type hotels but thought i would take my chances especially because in europe, the chain brands (like AC) tend to be more boutique-y. i will look into the AC Hotel Palacio del Retiro so i can familiarize myself with the area.
our son will be in madrid this summer and is supposedly going to be in the chamberi area ... seems a bit out of the city center but we'd like to be somewhere that isn't too far or too difficult to get to.
again - appreciate all and any comments :)