I stand on occasion but 95% of the time I sit while calling coyotes. I am typically colder when standing, am not quite as steady and feel more visible. Standing for long periods of time is hard on the legs and back as well. The one advantage is truly being able to swing 360 degrees if necessary. If I had more vegetation to shoot over, I would probably stand more than I do.
I use a Night Stalker tripod so I have the option of sitting, kneeling or standing depending on the terrain. It even goes prone but as I have gotten older, my back won't allow me to hunt from a prone position for very long. As far as a chair, I have used a lot of different ones. My favorite is the simple Beard Buster EZ Chair. I have ones that get me off the ground too, but this is the lightest chair and still fairly comfortable. It is so good, I bought a second so when the first wears out, I have a replacement.