Lots of options in the area, if you can share some preferences of cuisine we can narrow it down, but just a few good ones off the top of my head:

(All assume your friend has a car, all within 30 min of the Hilton)

Agora's Churrascaria - An all you can eat Brazilian BBQ on MacArthur & Main right next to John Wayne airport.
Darya's Persian - South Coast Village
Pascal's French - Bristol & Jamboree
Fleming's Steak House & Roy's Asian Fusion by Fashion Island
Orange Hill - American cuisine, Chapman Ave in Orange (nice view)
Chart House - Seafood & Steaks, Dana Point

All serve good meals, although none holds a candle to a really good pie floater