esperanza, thanks for the suggestion of Hotel Carlos V (3-stars). I'd narrowed it down to this one and to Hotel Pintor El Greco (3-stars) and finally decided on the latter. The former never replied to my email to whether or not they had double rooms with camas de matrimonio.

Hotel Carlos V did, however, have a good "Last Minute Special" of 75 Euros (breakfast not included) for the one night. Hotel Pintor El Greco DID reply and told me they DID have a cama de matrimonio so I booked through them and got a "Last Minute Special" for 56 Euros. Hotel Carlos V, in my opinion, is a bit more centrally located (next to the Alcázar) than Hotel Pintor El Greco (next to the Museum/House of El Greco just near the Tajo River.

I'll let you all know of my experience. That is to say, my REVIEW of the hotel. Saludos, MadridMan