I got a 2 day metro card with the (apparently now expired) Keisei skyliner deal and two trips to Tokyo later still haven't found the right time to use it. Occasionally the JR Tokyo local day pass at Y730 is helpful but staying near a Yamanote line station, the subway pass doesn't seem as cost effective. Probably would be different if my hotel was at, say, Akasaka-Mitsuke or Roppongi.