I stayed at the Tryp Madrid (near Opera metro) a year ago. 50 Euros sounds like a good deal to me.
I believe my rate was somewhat higher, but included a two room (very roomy) suite.
Gave my AAdvantage number at check-out; the clerk seemed incredulous that I don't carry the actual card around with me (for him to photocopy), but he took down the information by hand. I gave up the points for lost a few weeks later, yet they posted on their own after several months.
That location was convenient to shopping, museums and the EasyInternet facility a couple of blocks away.