I agree that this is a fabulous itinerary! However, as I finish up a back to back in a few days, I’m not sure it fits with the desire for beaches. Typical weather for at least half the itinerary might be too cold. I’d have to weigh that against the opportunity to visit so many wonderful places.
If beaches are a priority, maybe not the best choice, but I’m with those who wouldn’t travel that far for day trips to beaches even though I love beaches.