I can heavily vouch for Harvey Milk Photo Center, I go there all the time. Bring your negatives and paper, everything else is provided (easels, grain enlargers, base boards, enlargers, carriers, chemicals, etc.). The darkroom has 30+ enlargers, many different brands. Staff is very knowledgeable.
Yes, $10 for day access to the darkroom (which includes enlargers, and the chemicals are all set up by the staff). You can also get a partial membership (base fee of $64 for 6 months, which drops day pass price to $6, or unlimited membership for $160/6 months $319/1 year).
I guess it's a tad pricy, but the facility is really top notch, and I'm glad SF has such a fantastic resource.