rundsm - I'm really new to Herve Leger dresses myself, but since you haven't gotten a response yet I thought I'd say something. Since you're in the SF area, you might want to go to the Herve Leger boutique there to try on the dress, or some other Herve Leger dresses, to get an idea of your size. (High end department stores often carry them too.) Based on the size chart I'm an XS or S, but I just bought an XS dress and I realize I could have gone smaller - especially in the waist and hips (my boobs are a bit big). So I think the sizing can be a little tricky sometimes. On the bright side, since the dresses are so stretchy, being off a little can work - but I think it diminishes the fabulous Herve Leger figure-flattering effects.
Based on your measurements - 34 -32 -36, I would say an XS. Your measurements are really similar to mine (35 - 31 - 36). Our waists are much bigger than an XS would recommend, but I think the dress will cinch us in a lot through the tummy. I'm a 30 DDD bra size, so you can see from the 30 band that I have a small frame. I think for Herve Leger, your frame size matters even more than your actual measurements, since Herve Leger can squish in the chub, but can't squish in your frame! You can see a picture of me in a blue and black XS dress on page 276, with my 35-31-36 measurements.
I hope that helps!