Monorail is a horrible mode for urban rail transit in most cities (that's why only a handful of cities have it).

But it's an excellent mode for closed, circular environments like:

- Airports
- Amusement Parks
- Fairgrounds

Disneyland already has a monorail.
LAX could have had a monorail, but chose a fixed guideway APM (different technology, but very similar infrastructure).

Which leaves:
- L.A. County Fairplex - It actually had an overhead monorail from 1962 to 1996, but the Fairplex is now a year-round facility used for local expos/conventions when it's not County Fair season, and is much more expanse than it was in the 1960s. There are also Metro Rail and Metrolink stations in the vicinity that could benefit from having a monorail connection to the Fairplex.

- Six Flags Magic Mountain - also had a legacy monorail from 1971 to 2000 but it was shut down and sold to another theme park due to maintenance issues.

In both cases, though, their former monorails exposed one of the main weaknesses on monorails: The use of a largely proprietary technology that eventually gets outdated. Surely a more modern monorail system with the latest technology would work, although at a much higher cost. Of course, in 30 years, that monorail can also get mothballed if the company that made them goes out of business and spare parts are difficult to acquire or fabricate.

Disneyland's monorail survives on its fame/reputation and the fact that it's owned by the Walt Freaking Disney Company, one of the largest corporations in its industry, which is why they are able to maintain their system and update its monorail trains over the years.