My wife is flying to Los Angeles and needing a cab from the Airport to Wilshire boulevard. The computer says it will take about $70.00 fair, if true what would be a reasonable tip.?

That's what I would give, assuming competent service, driver who'd taken a bath, reasonably clean cab, etc.

Ten is probably fine if the cabbie doesn't have to help with luggage (hotel bellman have their "turf" on that one, for example).

One factor is just how "fast" the trip is for the cabbie, and not having been to Los Angeles since I was ten, I don't have any expertise on that one. An analog would be going from Salt Lake International to the U of U campus--either one of the hotels or the hospitals, for example, versus say, North Salt Lake or Murray right off of I-15, a freeway trip the whole way. There's no way to get to the "U" area without going through quite a bit of traffic, and even with the meter "kicking on" at lights, the deadhead trip back to the airport can be time consuming (assuming LA cabbies "work" the airport exclusively the way we pretty much do here).

And I hate to do an L.A. cabbie out of a good fare, but at the price outlined, a rental car ought to be considered an option if your wife is comfortable driving in a strange city.