You could also combine visiting Haight Streeet with continuing west past the end of the street into Golden Gate Park . Skates on Haight also rents rollerblades you can use to enjoy the park. Drug dealing is opposed by a neighborhood group but is now only more discrete. There are great ethnic restaurants on the street, and everything here is pretty cheap. There are also some great art stores including a Frank Kozik rock art store.
Many esoteric bookstores are fun to browse also.
Needless to say, you will hear the Grateful Dead frequently in this area. I think it may be cleaned up a bit since your last visit. Though you still see kids panhandling and can still buy pot easily, gone is some of the edginess there was even a few years ago. I see about 1 or 2 a week. This is due in part to the number of new shops that have moved in to what were vacant stores.