We had a wonderful stay at Amy's for an extended weekend girls getaway. It was only a block from the beach, and a good mid point between Marina Del Rey and Santa Monica. We got around mostly by walking, but uber/lyft is easily accessible and not expensive (<$10 to Santa Monica, and ~$35 to Hollywood).
The unit is the second floor of their house; one good sized studio with two (comfy) beds and a (not to comfy) couch/bed. It has all the basic needs, including a well stocked cupboard with beach material (chairs, umbrellas, beach mats).
Overall, would recommend!