I often vacation in Santa Monica, and this is my usual go-to place! It's really great-- clean, comfortable, and quiet! The beach is an easy 40-minute walk away. I really love the pleasant walk but if that's not for you, Uber can get you there really fast, or you can rent one of the many electric scooters that are scattered around the city.
Erin is a great host-- very responsive and available if you need anything, or will leave you alone if that's what you prefer.