Since you're in Manhattan Beach already, you can drive North on the PCH (it will start off as a 'street' then turn mor into a Hwy). This will take you to Venice, Santa Monica (you'll see the Peir - celebs there sometimes) or continue north to Malibu. When in Santa Monica, you get off by the pier and make your way to the 3rd street Prominade and various resturaunts etc and nice place to walk etc.

If you go all the way up to Malibu, you'll see some pretty good resturaunts right on the PCH with good ocean views. Gladstones, Chart House (Mel Gibson's spot) or a little further up is Dukes. You'll likely enjoy any of these places and Celeb potential is above average - but as someone else mentioned, they don't necessarily hang out the same places all the time and never know if you'll see one or not.

Closer by Manhattan Beach, going South on the PCH is Hermosa and the Redondo Pier - not bad for the views of the ocean and decent food. Go a little further South (within 20 minutes) and you'll get into Palos Verdes - Nick Cage and others live in the area and you may see a celeb (but I wouldn't bet on it.)

Hollywood and Bev Hills are other obvious choices, but if you don't have a lot of free time and want to be able to do something at night after you meetings, then N or S on the PCH may be your best bet. Also, if you get an entire day, you may want to consider going to Santa Monica (promenade area but on Second street) and catch one of the LA city bus tours. They will take you through Hollywood, view the sign, see celeb houses (at least where some use to live), Rodeo Drive, etc.

Good luck and have fun.