Well, if you are coming to San Luis Obispo for a weekend getaway, I suggest you arrive on Thursday. 

Thursday Night Downtown is great.  It's a local farmers market where they close down the main downtown street (Higuera St.) from 7 to 9.  If you're parked downtown, I think they have you move your car starting at 5.  Be careful, or you'll get a ticket.  Come down, visit the local merchants and have a BBQ sandwich from Country Time Deli.  If you get there early, you can walk around the San Luis Obispo Mission and then walk downtown once the street is closed off.  When you're walking downtown, its also a good idea to spend one minute or less as you dash down bubblegum alley.  Bubblegum alley is a narrow path between two buildings where everyone sticks their chewed gum.  It's strange and disgusting and a bit reminiscent of San Luis Obispo's more liberal days.

Friday is a great day to drive to Pismo Beach and see the monarch butterflies. The monarch butterflies migrate in January, so make sure it's the right season before planning a day to see the butterflies. 

If the butterflies are out of season I suggest driving up the coast to Hearst Castle. It's a spectacular drive and you can even stop to see the elephant seals that migrate through San Simeon starting in December and leave in March.  Be careful because it's mating season and plus the elephant seals are really big and they can squash you.

Reserve Saturday for wine tasting on the central coast.  Here are a few San Luis Obispo County wineries to hit.