We are planning to buy the 120 hour Madrid card which allows access to a lot of the museums there. Seems like a good deal if you are not limited to the number of times you can visit a particular museum. Does anyone know or have experience with the card-- can you visit say the Prado several times with the same card or is it good for only one visit to each museum? Thanks!
Validity
Once you visit one of the attractions listed as “free entry”, the personnel of the establishment will validate your card, registering the date. From then on your card can be used until its expiry date. Remember: the card is valid only for consecutive periods of time.
Once the card has expired, it can no longer be used. For example: a 24-hour card activated at 1:45 pm on a Monday will be operational until 1:45pm on Tuesday.
Museums and attractions listed as free entry
Not all cards have the same characteristics or participating establishments. Please ensure that the one purchased suits your requirements.
Cardholders can visit the museums, monuments and other attractions a single time. Generally, the cardholder is allowed into permanent exhibitions but temporary exhibits are not always included as part of the free entry.
All pertinent information can be found on the guide that is included when you purchase your card or through each of the card´s websites.
According to this page, under "Validity," it's only good for a single visit to a sight: http://turismomadrid.es/en/get-organized/madrid-card.html
Edit: I see DJP beat me to it!
That's a shame. It doesn't appear to be worth it-- you certainly can't experience the Prado on one or even two or three visits. Thanks for the helpful responses. I'm glad we found this out before we bought the card.
I'm not sure how long you plan to be in Madrid for, but nearly all Museums offer free entry for some of their hours. Take advantage of this, along with the very cheap metro system.
What you are looking for doesn't seem to exist, but here are some alternatives to save money on Madrid's museums.
A Paseo del Arte ticket is good for one admission each for the Prado, Reina Sofia, and Thyssen Museums, and saves a few euros over buying individual tickets. It also saves having to wait in ticket-buying lines once bought; if you buy it at the Reina Sofia or Thyssen, the lines are usually short.
If you are going to the Prado multiple times, there's a "two visits in one year" ticket for €22 (a single visit is €15) or for $100 ($80 of which is tax-deductible, according to their website), you can become an "American Friend of the Prado" and get unlimited visits: https://www.afpradomuseum.org/join/mode/21060.
I visited the Museo Sorolla and the Reina Sofia during their free hours, and neither one was too crowded for me to enjoy (I was prepared for huge crowds at the Reina Sofia, and even at the Guernica, they weren't too bad).