If you are going to be in downtown SF, there are two main places to smoke.
1. The Occidental - a small cigar bar where you can actually smoke indoors.
http://www.occidentalcigarclub.com/home.html
2. The Cigar Bar and Grill - you can smoke outside on the patio, but they have heaters. If the is nice weather, great place. No one bothers you while you are smoking.
http://www.cigarbarandgrill.com/
Otherwise, I would check out Grant's on Market, great selection, although the prices are not great with CA taxes.
http://www.grantspipeshop.com/