The Best way to watch the 24 Hours of Le Mans.

The 24 Hours of LeMans is more than just a race, it's an experience everyone should try at least once in your life.  
If getting to France is not possible you have several options to follow all the action on the Circuit de la Sarthe.

In the US, your worst option will be broadcast TV.
Fox Sports will carry 12 hours of the race on cable,  only 5 and 1/2 of those hours on the  widely available Fox Sports 1 channel with the remainder on Fox Sports 2 which many providers do not carry in HD if at all.

However, Fox will be showing the entirety of the race on the Fox Sports Go App and web site.
 
In addition to the world feed and commentary by the team lead by Bob Varscha, you will have access to onboard cameras on the two Corvettes and one for the pit crew.
You have to be a subscriber to their service via your cable package to have access, if your provider does not carry Fox Sports you are out of luck.

I suspect that most fans automatically expect the booming, indefatigable voice of John Hindhaugh   commenting any race lasting longer than two hours.  
We will be tuning to hear him and the team on the Radio Le Mans web site.   Hindy will also be commenting on the  Porsche, Audi and Nissan web sites where you will find onboard cameras from their respective racers.  Also here on YouTube

Your best option is the official  WEC app.  The basic app will provide you with timing and scoring info for free but for $9.99 you can purchase full access to the Le Mans race.

That premium subscription will give you live video, multiple camera feeds, driver bio, highlights...the works.    Unlike the F1 app,  WEC was able to link the app subscription to their web site so for the same ten bucks you can have the main feed up on your laptop and follow the extras on your mobile device.

The app is available at the AppStore  and GooglePlay.