Another one for ignore it. Unless it's really really in my face (which she rarely is) we overlook it and continue to keep our tone light, but firm. I'm not going to make a mountain out of a molehill, and asking a 16 year old to never ever have an attitude is, imho, really unreasonable. That doesn't mean I put up with disrespect, but it does mean that I'm not going to keep her in trouble all the time.
If she's really bad about it we gently point it out, "Hey, you don't need to talk like that ; I'm not threatening you, we're just talking. Can you try that again?". We also have a rule that if she doesn't like the way we've said something she can ask, "Can you rephrase that?" and are working on the difference between, "that MAKES me mad" and, "I FEEL mad when you say that" (e.g. taking responsibility for your own emotions, and understanding that no one but you controls that). So far this approach has worked really really well with her really severe anger problems. After two years has turned into just a relatively normal attitude.
I have a stricter rule with the way she treats the little ones in the house, though... sometimes she can carry a tone over to them or speak in unfair ways, and we're quick to call her on that (subtly, so not to needlessly embarrass her). If you consider it as not something they do on purpose, but more of something they may not realize they're doing (I realize this isn't the case all the time, but stay with me) it makes it easier to approach the behavior in a respectful way without adding fuel to a fire. If you think about it like your teenager is being malicious and awful to you 24/7 it'll just make it that much harder for you to talk... and I do realize how hard it is NOT to take it personally.
Respectful conversation is REALLY important in the house and to be honest I think the best thing we've done to improve her communication is to model it. When my husband and I fight we try to resolve it quietly and openly, keep our voices low (though sometimes too firm! No one's perfect!), call each other on sarcasm, model walking away to cool off, and are sure to show those around us that we've made up and were able to work it out. I don't believe that running and hiding to finish a disagreement helps anyone... and M has told us before that seeing us have an argument and make up may be slightly uncomfortable (is it ever awesome to watch someone fight?), but
she's admitted to eavesdropping many a time to see how we talk it out... and then using the words we've used to try and work out arguments with her boyfriend.