If you're an experienced traveler and have been to Tokyo before, why do you need a guided tour? Japan is incredibly easy to get around in.

Since you're coming from outside the country, just read a guidebook (supplemented by the PDFs from the Japan National Tourist Organization website), figure out where you want to go, buy a JR Pass, and have fun.

If you need economical accommodations, there are clean, safe, and reasonable (if someone lacking in amenities) business hotels in every city. In some locations, there's a tourist information office in the local train or bus station that will find accommodations for you if you don't have a reservation. For food, just wander around until you find something that looks appealing.

Don't worry about traveling solo. I and other visitors to Japan have had the delightful experience of being "adopted" by groups or families. It's easier if you speak the language, but I know people who speak no Japanese who have met up with a Japanese family at some famous site or other and have ended up with an invitation to join the family's next excursion.

The Air Pass can be handy if you have little time and want to visit far-flung locations on the same trip, but on the whole, I prefer the up close and personal view of Japan that you get from the train. It's also easier to meet people on the train, both Japanese and foreign.