Can anyone tell me the benefits of becoming a LLC when working with different companies?

First, it is an extra layer of protection from being sued if anything happens on the job site. Second, it allows you to open a SEP retirement account and contribute 25% of all monies that are paid to the LLC tax free up 45-46 thousand per year. Finally, it allows you the opportunity to start a business without any employees and receive the tax benefits that go with it...i.e. mileage, CEU's, travel expense, and many more which will lower your tax bill significantly.

Eric has outlined everything perfectly.

I have several businesses each an LLC and it's the only way to go for total protection.

 In my area the normal costs of setting up an LLC with an attorney is $1440.

You may go on line and do it yourself without the assitance of a professional.