I've stayed in Santa Monica a few times, and this place is my fav.
Kelly works in interior design, so you know you are dealing with a thoughtful host and someone who genuinely cares about your experience. Her place is cute and perfectly clean and tidy, and it's a nice walk to the beach (depending on how fast you want to walk--oh, and be prepared to say "hi" and "good morning" to the people you'll pass on the way as it's California, after all).
The bed is comfy, and the sheets and towels and stuff were high quality. Honestly it was more comfortable than staying in my own bed, so I probably need to do an upgrade when I get home. : /
Down the street from her place you'll find a nice coffee shop and grocery store. It's located perfectly if you want to spend time on the beach or go into LA proper. Plenty of parking on her street, and it's a safe and quiet spot.
She has a super sweet dog English bulldog (I think!) named Girlfriend, too! I'm slightly allergic to dogs, and I didn't have any probs with the room or space.
My one complaint? That I'm on my way back to NYC where it's snowing and 25F instead of still being in California.