We stayed at Rhythm a few years ago, and enjoyed it very much. The building is gorgeous, and the food was good when Wolfgang (owner and chef) was cooking -- not sure if he still does it. It is an excellent choice if you do not want a fussy Victorian decor. There is parking on site, and bicycles to use, and a beautiful view of the ocean from the window-filled common room.
The disadvantage is it is pricier than some of the other B and B's and it is a bit of a hike into town. If you are going in high season, it may be an advantage to be out of the crowded part of town, and there is a trolley then.
Two other pampering places not near the center of town we recommend are the Mission Inn (no ocean view) and Peter Shields Inn.
Other B and B's we recommend are the Saltwood House (on site parking on Jackson street!), Mason Cottage (great porch, but street parking), Bacchus Inn (street parking), Carol Villa (off site parking, and more of a hotel feel), Windward House (off site parking). None are on Beach Ave, but are close to beach, restaurants, shopping.
If you want to be on Beach Ave and in the center of town, I recommend a penthouse suite at the Marquis de Lafayette hotel. Great oceanfront views, on site parking, nice breakfast buffet, kitchenette, pool, for about the same price as a B and B. Call for best price.
There are very few places you can go wrong. We have been going as a couple for years, and have stayed at about 15 different places, mostly B and B's. I am sure you will enjoy your stay!