SLO is basically a college town (Cal Poly SLO is there). The only restaurant there that has been recommended to me (I've never tried it) is Big Sky Cafe, which is kind of a farm-to-table cafe. Friend of mine said he had a good lunch there.
Fortunately, SLO is within a reasonable drive to lots of good stuff.
Swing over to the coast on Highway 1. There's Morro Bay with the Morro Rock. Worth a stop just to check it out. You want seafood? Tognazzini's in Morro Bay.
Or head up the coast from Morro Bay toward Cambria. Before you hit Cambria, you'll drive by Harmony, population 19. Worth a stop just to get some ice cream from the Harmony Creamery. Stroll around the town for a while. There's a glass-blowing place and some other shops.
Then back on the 1 up to Cambria. Cute little town with lots of little shops and eateries. Linn's was pretty solid for breakfast. They got a dude there who's kind of like the Soup Nazi -- on the gruff side, but he's alright if you play along with him.
North of Cambria you'll hit San Simeon, which is where Hearst Castle is. As I indicated in another post, the Castle is closed, unfortunately. But right off the 1 on the ocean side of the road at the bottom of the hill from the Castle is the Hearst Ranch Winery, with tasting tables that are just adjacent to the beach and pretty solid wines. Great place to take a picnic basket, do some tastings, buy a bottle of wine from the winery, and enjoy the view. We had a great time there. Make a reservation.
North of San Simeon is where you really get into prime elephant seal, etc. viewing areas. Beautiful coastline to just drive. Head as far north as you want up into Big Sur. There's a million places to stop and enjoy the view, do a hike, etc.
Or head north from SLO toward Paso Robles. Wife (no pics) and I stayed at a place out in the sticks halfway between Paso and the coast, right at the intersection of Hwy 46 and Old Creek Road. The place is up on a hill looking down over a vineyard. Was very peaceful.
There are a ton of wine tasting rooms in and around Paso. Check out the Tin City area which is an old renovated industrial area with tasting rooms, a brewery or two, restaurants, shops, etc. It's located just off the 101 south of Paso between Paso and Templeton. The wife and I liked Union Sacre and Jacob Toft. Turtle Rock was a little stuffy, but the wines were good.
And there are a bunch of wineries/tasting rooms in Paso itself and west of the city up in the hills.
Food in Paso: Try Les Petites Canailles for something upscale. Il Cortile for Italian. Both were very good. For a steak and cool experience, head east to the little town of Creston and try the Loading Chute. Breakfast: Joe's.
If you go south from SLO on the 227, you get into the Edna Valley wine region. Lots of wineries in that area. I prefer the Paso area wineries, but there's some solid ones in Edna Valley as well, including Baileyana and Claiborne & Churchill.
You mentioned going down to Santa Barbara at some point. Good idea. Lots to see/do/eat/drink down there. That's a thread unto itself.
On the way south, you'll go through Nipomo. Jocko's Steakhouse is the spot there for dinner -- either going down or coming back. Or hit the Far Western Tavern in Orcutt for another meat coma experience.
Farther south but before you hit Santa Barbara proper, you'll be going through the Santa Barbara wine country/Santa Ynez Valley. More great wineries all over the place. That area is worth its own thread, frankly. The wife and I love stopping in sleepy little Los Alamos and hitting Bell's (French cafe type place) for lunch, or Bob's Well Bread for breakfast, or Pico or Full of Life Flatbread for dinner. There's also Babi's Beer Emporium -- grab a beer and hang out on the patio. Los Alamos also has a few tasting rooms in town. Los Olivos has even more. In Los Olivos, I recommend Brewer-Clifton, Evan's Ranch, Carhartt, and Dragonette. Walk next door from Brewer-Clifton to Figueroa Mountain Brewery when you're sick of tasting wine and need a beer.