Both Edna Valley and Paso Robles are excellent wine tasting destinations. Edna Valley is closer, of course, but both areas should be quiet in February.
San Simeon is about an hour away from Avila Beach. If you're planning on Hearst Castle, be sure to drive a little further up the coast and see the elephant seal rookery where there are literally hundreds of seals laying on the beach. This is where they bear and rear their young. It's quite a sight.
On your return from Hearst Castle, visit the quaint town of Cambria. Moonstone Beach Drive has a boarwalk for enjoying a walk along the shore without stepping on the beach and sand. There are two "villages" in Cambria. Both areas have unique shops, including art glass, paintings, an herb shop, etc. Cambria has some of the area's best restaurants: Robin's, Sow's Ear, Wild Ginger, Black Cat Bistro.
Montana de Oro isn't really the kind of place you can walk around. The main road into the park is narrow and has little to no shoulder. However, the trail leading out to the bluff edge is a very easy walk and loops around back toward the parking lot.
The Village of Arroyo Grande is a western themed shopping district just south of Pismo Beach. There's a swinging bridge behind the south side shops and a small park there.
If you like a hot tub experience, visit Sycamore Mineral Springs and rent a hot tub for the hour. The tubs are located on a wooded hillside in private settings.