AS budget travelers we try to avoid taxis and other expensive forms of travel, especially with the current rate of exchange being rather lopsided , dollar to euro. Have not flown into Madrid from U.S. before. Arrive in early October in a.m. on Lufthansa from Frankfurt. Staying in vicinity of metro station at Puerta Del Sol. Love the nightlife of this area, very vibrant and exciting. Any tips for staying in this area and inexpensive transportation to above mentioned area deeply appreciated.