Avila has the best boardwalk/beach area of the three imo. Shops, wine tasting, pubs and restaurants all along the beach. They also have a
great dog beach if you travel with a dog.
Libertine has a pub there with a lot of their beers on tap plus some guest taps. They specialize in wild ales and have a pretty solid lineup.
Pismo is nice, but it gets obscenely over crowded there with parking and people. If you wanted to stay somewhere closer to here, I'd suggest Arroyo Grande. It's back up away from the beach more but like Avila it has a nice walking area with quite a few wine tasting rooms also..
Mason Bar is a must hit place even if you're not staying in AG.
Doc Berstiens Ice Cream is a great too
Haven't been to Santa Maria in years.