The choices are basically Santa Barbara, Pismo Beach, San Luis Obispo, Morro Bay, Cayucos, Cambria, San Simeon, Big Sur, Carmel, Monterey, Pacific Grove and Santa Cruz. All are at the ocean except San Luis Obispo is inland. All are pretty small towns except Santa Barbara and Santa Cruz are bigger. As far as being "lively," I don't think of any of those as lively, party-town type of places. But hopefully others here on this forum will help with specific suggestions of places to have cocktails.
Typically we give a recommendation for one night at the south end of the Big Sur region, such as Cambria, San Simeon or Morro Bay, and another night at the north end of the Big Sur region such as Carmel, Monterey or Santa Cruz. However those might not be the right choices for you.
You should figure out what you want to see and do on those days, then pick a place to stay that is near them. Stay near what you want to see and do. Here is a travelogue posted by another member of this forum. It only goes as far south as Pismo Beach, but it gives you a good idea of the sights that are available along the central coast: https://picasaweb.google.com/Mjneenan/Califo…
When you pick the 2 locations, go to the local forum for each one and read the top questions, and start a new thread in that local forum. Members who read that forum including the destination experts will help you fine-tune your itinerary in that location with tips and suggestions that are appropriate for you and your interests.