traveling to barcelona and madrid in august, looking for recommendations for a good hostel in the center of the city near the sights. solo traveler, woman in mid-30's.
Search on hostelworld.com - there are descriptions and reviews. There's another similar site but I can never remember the name.
First, you've posted your questions about accommodations in the various "Reviews" sections. These are intended for those who've already taken trips to post their experiences. If you don't get answers, repost in the main country sections of this Forum.
Second, in addition to Hostel World, my sister recommends Hostelbookers for reviews: http://www.hostelbookers.com/
Third, I'm a fan of EuroCheapo for recommendations, although I always book directly with the hotel. In addition to reviews, they have lots of great city tips: http://www.eurocheapo.com/allcities.html
Fourth, in Spain, a hostal is not a hostel, but an inexpensive, basic-but-fine hotel (like a pension or guesthouse in other countries). If you budget can stretch to about €55 a night for a single, I highly recommend the Hostal Acapulco in Madrid. If this website shows up in Spanish, click the British flag to change it to English: http://www.hostalacapulco.com/
My partner and I were just in Madrid a few weeks ago, and we booked an really reasonably priced apartment with Sol Square Apartments. 3 nights came out to be 199 euro total and the apartments itself are really nice - clean, modern, spacious and the location can't be better. It was between the Vodafone Sol and Opera metro stations, and literally a few feet away from Chocolatería San Gines (very dangerous)
For a true hostel experience, I really liked the TOC hostels. We stayed in the one in Sevilla but there's one in both Madrid and Barcelona.
€199 for 3 nights might be a good price for a couple, but hardly for a single.