K.C.
Las Brisas is a yummy Mexican restaurant right on the beach in Laguna.
5 Crowns is a great steakhouse in Newport (maybe technically in Corona Del Mar, but close enough to Newport).
For a great treat, check out the Shake Shack in Crystal Cove. http://www.yelp.com/biz/rubys-shake-shack-newport-coast
Sherman Library & Gardens also in Newport/Corona Del Mar is a beautiful place to walk around.
Laguna is really nice just to walk around. There are lots of art galleries, shops, and boutiques. There are good little cafes and ice cream shops, and a nice path to walk along the beach.
You will be able to catch the last few days of the Sawdust Festival in Laguna. Don't miss it! http://www.sawdustartfestival.org/
Pageant of the Masters, also in Laguna, closes on August 31. If you can find a way to get tickets, it is truly an amazing show. It is VERY much worth the price to get good seats - in the middle and not too far back. The show is much, much better if you can see it well. No matter where you sit, bring binoculars. Most likely, it is sold out through the box office, but try craigslist for tickets. There is also a Festival of Arts on the same grounds as the Pageant and that is also definitely worth a visit. www.foapom.com
Roy's is a good restaurant in Newport (I think in the Fashion Island mall). It is a chain, mostly in Hawaii and So Cal of Hawaiian fusion style food. Their chocolate souffle is great!
If you can get a reservation at Pizzeria Mozza (owned by famous chef Mario Batali), that is also worth it! I think you can call a month in advance. Lunch reservations will be easier than dinner.
Have fun! Laguna is one of my absolute favorite places!