Not sure what you meany by American cuisine since that's such a broad category (steak & seafood? meat & potatoes? FreshExpress greens for salad?).
If by "American" you'd consider CA cuisine or American-something, then Alan gave some good recs. El Toritos and Pedros are loud, casual places but fun if you like standard Cal-Mex.
If you're looking for an organized group event type of dinner, here are a few recs that my husband's company or I have used in that area for large goups, that serve food that looks like hotel food but actually tasted like real food. Links to their menu included so you can decide if the food's similar to what you're looking for.
David's at the Santa Clara Golf and Tennis Club (CA/American)
(which I've been to for an event luncheon, a little better than hotel food)
La Fontana at the Great America Hilton (CA/Mediterranean)
Parcel 104 at the Marriott (CA/Seasonal
)Run by one the Bay Area's "star" chefs, I think the food is very good (if not on my dime), but portions are small and "precious" and not what I think of as American.
Note: Parcel 104's private rooms are in small, windowless hotel function rooms, but they can prob seat your group in the dining area if you don't need a private room.
Places my work has used:
Lion and Compass (CA Fusion)
El Toritos (CA Mexican)
Pedro's (CA Mexican)
Marianis (American Italian)
Faultline (Brew Pub/CA Fusion)
Places I have heard about:
"American cuisine" doesn't stand out in the area, to be successful a restaurant has to have an edge. You may want to try hotels if you have to have "American". Many of the "American Cuisine" Restaurants in the area were chains (Velvet Turtle/Charlie Browns/Fish Co) that died from mergers and acquisitions and were replaced by restaurants serving other cuisines. Last time I ate at Lion and Compass I had braised short ribs with a wasabi sauce, mashed garlic purple potatoes, salad w/ Asian dressing: that is what sells in the area. The restaurant row on El Camino is either a chain/chain fast food/ethnic.