The Monorail

yes it will cost a lot. In the millions. Plus they have to find an area to build an airport station, then they have to create the infrastructure for the rails and station to get to the main airport terminal. Maybe only a fraction of what they spent to build the system itself the problem is that nobody wants to spring for the money to build that extension. Many feel that the taxi/shuttle/rental car system takes care of transporting people from the airport for now and don't want to spend a few million to extend the monorail to the airport. As in other cities (like Honolulu), people always wants the feds to fund or partially fund their transportation systems so until that happens the airport extension may not happen. And yes there is a big push by the taxis to kill the idea, they would probably lose at least 15% or more of their fares to the east side of the strip, they would lose millions if a monorail extension were built.

While the west side of the strip has a piecemeal tram system it cannot be used to effectively transport people around, it sometimes is faster to just walk instead of walking through the casino to get to their tram stations. The west side trams aren't close enough (you still have to walk from excal to monte carlo, and bellagio to mirage) to be effective

If those making the decision weather or not to side with the cabbies rode with them undercover as innocent tourists, they may change their minds.

The LV monorail only operates the stations between MGM & Sahara. The ones on the west side are all individual, private tram operations run by the various hotels. That accounts for the big gaps in service on that side. It would be nice if the gaps were closed and there was full service on both sides, but that will never happen.
The extension to the airport (about 4 miles - effectively doubling the length of the system) would indeed cost far too many millions to ever happen. Too bad, since they were looking at placing stations at both Terminals 1 & 3. That would have been so convenient for visitors to get to and from the strip!