I'd like to teach my dog some alternatives to growling / snapping at people. Ideally, I'd like for him to just get up and walk away instead of growling or snapping at someone. Obviously, if he's cornered, or the person follows him - that's a different story.

He likes to be petted only on his terms. If he's stressed out by other triggers, and someone tries to pet him, he may growl or air-snap.

I've become pretty good at monitoring his signals, and giving pretty clear directions to any house guests on how to interact appropriately, and I don't let strangers touch him, so the rate of these occurrences has gone down significantly since we've got him. There is still the odd occurrence though.

Tonight, he was sitting up next to my husband who was petting him, and he started growling. I'd prefer if he would just get up and walk away when he's uncomfortable. Can I teach him to do this?

I'm not real sure but you might be able to modify the place command. When he growls or acts out or looks ready to tell him to lay down and stay in a designated spot. Like a time out to calm down. Hopefully he will get the hint that if he wants attention he is going to have to chill out or if he is going to act that way then he has the option to leave, that you don't want him by you in that state of mind. Make it his spot. No one messes with him when he's there.

https://thegooddog.net/training-videos/free-how-to-training-videos/learn-to-train-the-good-dog-way-the-out-command/

30:12
Learn To Train The Good Dog Way: The "Out" Command
YouTube - Dec 22, 2015

Thanks for the input.

Twister - I like that idea. I can gauge pretty well when he's getting a bit moody, so i should be able to spot when he's getting towards his limit and intervene then. Of course, I need to teach him to "go mat" first. He has so many different things to learn & issues to work on, I just had to pick a few things i found most important and deal with those before moving onto anything else. Will move "go mat" up on my priority list.

Thanks for sharing the video, Amy. Not sure it's quite what I need for this, but still an interesting watch.

Essentially, you are teaching the same thing except your using the term go mat while he's using b out. Also search his videos for the place command.