Thanks for all the replies.
Arrived Friday at 9am to the hotel, and was lucky enough to be able to check in!
Was given a nice room facing the courtyard (very quiet in back, slept well!). I hadn't booked the cheapest room, I went for "Executive Deluxe", the next level up. Was upgraded (I think) to this room, though not sure if it's an upgrade, no matter as I was also given Club Lounge access! Very happy with that, especially as a lowly Platinum Ambassador.
The lounge is quite good, with an extensive breakfast spread and snacks all day. Drinks (for sure beer plus soft drinks, and wine in the evening) available most of the day from what I saw.
I took at look at the downstairs restaurant's breakfast spread, and while it's a tad bigger, it's not that different from the lounge--I'd recommend staying in the lounge, even though the agent at checkin told me I could take my breakfast at either place.
Lounge service is quite formal and full-on white tablecloth every morning. Don't wear your shorts and flip-flops!
Very happy with my stay.
Also--the trip from the airport is very easy, and quick--less than 30 minutes. Buy a 10-trip card for EUR10 (includes Airport fee), and you can use it on buses and subways.
From the airport:
Take the airport line to Nuevo Ministerios, and switch to the blue line. Go just one stop to Gregorio Maranon, get out and it's about a block and a half away.
To the Museo del Prado:
For trips to the Prado, the bus is actually much faster than the Metro: The bus about 100m from the hotel takes you directly there in about 10 minutes. This hotel is not that far away from the action, though probably not walking distance. The area, while quiet at night, is a nice neighborhood.