4 p.m. until 11 p.m. on a Saturday (including deplaning and then returning to the airport, getting through security and to your gate). Rather limited options. What were you thinking might be your options? Going to a museum or skiing not practical, even if you could get there and back in your timeframe. If you get off the plane quickly, and can check your bags for your return flight right away, the winery or the Graber Olive House (listed on Tripadvisor as #2 on the list of things to do in Ontario) might work. I think Ontario Mills is, sad to say, your best option. You could see a movie and get dinner if you don't want to shop; there are two multiplex cinemas-- one inside the mall and one outside-- as well as a comedy club, whose name I can't recall. I saw a Quakes game and enjoyed it, but it'd be quite a cab fare r.t., whle it appears there is a free shuttle to Ontario Mills (I have not taken it).

I've been to ONT many times (my sister and brother-in-law live in nearby Upland). The airport is much less hectic than, say, LAX, but neither the airport or the surrouding area are the best for killing time. Note that once you leave the secure area of the airport, there is no place at all to eat. Some nearby hotels (e.g., Marriott, Holiday Inn, Ayres Suites) have decent restaurants and bars. As I recall, the airport Doubletree has an active bar/disco. A couple of years ago we ate at a good Indian restaurant, the Bombay, on North Vineyard--short cab ride or long walk from the airport.