[Nyororin]

To add some additional information about capsule hotels and why I cannot recommend one for anything other than a one night experience;
In most cases, there will be no place to store your luggage. They really are a "sleeping-only" sort of arrangement. For each capsule there is a small locker, but I have never heard of one large enough to accommodate even an average sized suitcase. Sometimes they will let you store your bag at the check-in counter, but I have heard of people needing to squeeze their bag into the capsule with them - making it virtually impossible to sleep.
Either way, during the day you will be responsible for your bag. You`ll need to lug it around with you wherever you go. Definitely not something that would make for easy sight-seeing.

The baths at capsule hotels are of the sento variety. This could be a negative feature for some people. It would be a communal bath with no privacy whatsoever.