Watch others in the department; those who have been in the company for a few years. Just do what they do, and toe the company culture line.
Imo, Standing is a bit much--it almost feels confrontational. Personally, as a show of respect, I normally stand and say thank-you as they depart.
You may laugh at this, but I am an avid tea drinker, and have a small collection of teas piled on my desk. I typically have a largish French press of tea sitting next to me as I work. I always keep a few empty paper cups handy, and offer visitors a cup of tea. It's a great show of goodwill. Some chuckle a bit and decline, but those from tea-drinking cultures tend to really appreciate this offer. Then you end up sharing teas, and trying new stuff. You'd be surprised how many other tea drinkers you connect with in this way. There is a certain peace associated with tea.