One thing about doing Passport Weekends are fun especially if you do not drive. I totally recommend getting a driver or joining a tour bus program.
I think its a good idea to do Wine Walks too but that doesn't give you the same experience at the actual wineries.
Here is some opportunities
Stay and Let Them Drive from MacCallum House Inn you can stay and try some great wine tour as a group or private.
There is the option for you to do it on your on Hopland Wine Trail from Organic wine making to Pinot Noir you will find winemakers.
If you want you can take advantage of the Designated Wine Driver that is Great Deal with Amador Wine Driver check it out.
Paso Robles is a great location and rich in amazing wineries that you could take yourself but there is always the Grapeline