I wouldn't be too offended by 'you guys'. I have a woman friend who says that all the time, doesn't matter who she's addressing, and her little daughter says it too. And let me add, she is no feminist.
Here in Oz, men often call other men and women 'mate'. Now I hate that term, but its part of our culture, and you can't fight something that is so ingrained in the culture. ๐