Just make sure it is at least mid thigh, any shorter and it will look like you forgot to put your pants on! If a company allows the casualness of open toes and heels, I would be surprised if they would require hosiery.
Women Wearing Slips, Bras, Panties, Hose and Pantyhose
When you go skiing you can live in thick socks and boots! Not to mention the fact that pantyhose can help prevent issues with your legs when you get older.