You can always ask for a taxi, but the cheapest and most popular option is Uber. Uber will pick you up and drop you off at the destination you choose. You tell the app your pick up location and drop off point. Once you get in the car, the driver will know where your going. So cool! You can pre request a car at a certain time. But in San Francisco you can open the app and request a car which will be at your door in less than 5 minutes.
Download the app on your phone before you leave and create an account.
Your hotel to Pier 33 is one mile. Most people would walk it in about 20 minutes.
I would walk up Sansome. 30 minutes should be more than enough time for the walk.
An UberX would be about $7.