SF is really that bad for finding a good suit! Man, that's a bit depressing.
There are lots of good suits here, just depends what you're looking for (besides just "slim"). Brooks, Barneys, Neimans, Ralph Lauren, Wilkes, even Nordstrom, Bloomies and Saks all carry good suits. Some are slim. Styling will be different with different brands and models. Look, try, buy.