Prego, 18420 Von Karman Ave., Irvine. Open Sundays till 10, Mondays till 10:30, Tuesdays through Thursdays till 11, and Fridays and Saturdays till midnight. (714) 553-1333. Frazzled after a day on the fast track? Try a glass of Chianti Classico or a Sambuca Romana at Prego: It may be the best yuppie/muppie (for middle-aged) bar around here. On warm summer nights you can sit outside on the patio, where there's jazz on Thursdays and Fridays and chamber music on Saturdays, starting at 6:30 p.m.