I see lots of ads for 2-girl shows. Some providers even offer to bring a male companion. Of course everything varies by juristiction, but generally speaking- if there is no sexual contact between you and the provider(s) and you are just paying to watch them get it on in person...legal or illegal??

My opinion:

You are still paying somebody to have sex, even if it's not with you.  In almost every US jurisdiction, payment for sexual services is illegal.

So no, it's not legal to pay two ladies to get it on while you watch.