I have stayed at Hostal de los Reyes Catolicos and I would compare the ameneties with a Hyatt Regency or a Marriott (i.e., I didn't find it all that special). The Buffet breakfast is nice, but it's also quite expensive and it's no better than what one encounters in Business Class hotels in the U.S. And the way the place is laid out, one needs a map to find the way back to one's room.
I have also stayed several times at Hostal Hogar San Francisco (about 200m behind the Parador, past the Facultad de Medicina). It's a 'working' Franciscan 'Convent' (Friars, not Nuns). 'Standard' rooms at HHSF are spartan. But they have one room, the Cotolay room, named for the Carbonero who helped Francis of Assisi build the Convent, that's a real value. It's huge! I would estimate it at 625 square feet. It has one Queen-size bed and a sofa that converts into a single bed. The Cotolay costs a bit less than a standard double room at the Parador but I think it is a much better dollar value (if it's available, that is)