mod. price hotel in Madrid, Barcelona, Seville

Hotel Europa in Madrid: one of the greatest bargains I have encountered. Beautiful hotel in a perfect location right on the Puerta del Sol with extremely helpful staff. The cheaper rooms don't have a view of the square, but they are blissfully quiet. Hotel Maestranza in Seville: centrally located just a couple of blocks from the cathedral, lovely staff. Hotel Continental Barcelona: one block from Placa de Catalunya on the Ramblas. Again, the cheaper rooms lack a view of the Ramblas, but are very quiet. It's kind of quirky and very pink, but very comfortable and has a complimentary 24 hour buffet.

Madrid - I like Hostal Montecarlo and Hostal Phillip IV on Gran Via in the same building. Both central location and near the metro. (I have read that the stop beside them is closed for updating through the middle of September, but another stop is near by.) Check out www.madridman.com for others. Sevilla - I would consider the Hostal Santa Cruz in the old area. Have not stayed there, but did go in it on my last visit. Very nice and reasonable.
No metro in Sevilla. Will need a taxi from the train station.

Hotel Opera in Madrid is centrally located. Minutes from the Royal Palace and a short walking distance from Plaza Mayor. The Opera metro stop is very close by. The staff is very helpful. I stayed there earlier this month for 6 nights.

I'll second the Hotel Continental in Barcelona. While I wasn't fussy about the room itself, the bathroom was very clean and could sit out in the common room on a balcony with wifi and make use of the free food & drink. I would stay there again just for the location (but maybe pay a bit more for a larger room).

When I visited Barcelona I stayed at Hotel Moderno. It is 3 star Hotel that is quiet, clean and 5 minutes from Las Ramblas and the Metro. They had complimentary Breakfast, Free Wifi, and the staff was very helpful. Hope you enjoy Spain!

If you are staying for minimum three nights then I recommend you rent an apt. Our first choice is to stay in short term rentals.

While not really moderately priced, I found the recently renovated Hotel Granvia to be a good deal in an excellent location. If you mention you are a RS reader when booking by email, they may offer you a better price or include breakfast (in my case). Your text to link here...

I have no idea what you mean by moderately priced. You might look at http://www.eurocheapo.com (scroll down to get their city list). While their cheapest listings will be hostels with shared baths, their more expensive ones will have ensuite facilities. Even if you don't use places they recommend, they also have very good neighborhood descriptions that are very helpful in deciding where to stay.