It would help to know how your driving. Are you going to go east on the 58 and down the 395, to the 15 and west, are you going down the 5, east on the 210, or down the 5 and east on the 10? Once you know, please ask your question again with Italian in San Gabriel Valley, or Italian in Ontario Pomona area, or Italian in Pasadena, Arcadia Monrovia. That will help narrow it down, as well as what you want, southern italian, italo-american spaghetti house, risotto palace, etc. g'luck.
My favorite Italian restaurant in LA thus far has been Vincenti, at 11930 San Vincente Blvd. near Montana in Brentwood.
The menu is a little spotty - some of my compatriots' dishes left something to be desired - but my meal was one of the best I've had in LA.
They have an impressive bar and wine list, too.
When I went there, the 5-course tasting menu was $60 a person - to give you an idea of the cost.
Not a classical Italian Bistro, obviously, so it may not suit your needs, but I HIGHLY recommend this place as a restaurant to try.
My most vivid memories are a lobster risotto, some homemade venison sausages, and my first bottle of Gravello, a historically interesting super-tuscan that is kind of difficult to find.