Assuming you are in business, If you do fly from 4, then attempt to enter the VS Clubhouse...most likely you will be unsuccessful. I was fortunate to gain access a number of years ago as I flew business, PRG to JFK on DL. Even though it was not a valid routing to access Clubhouse. I played dumb and prrsented my DL boarding pass. The agents (appparently ignoring the PRG signifier) and (swayed by) my description that their club was like Gucci compared to Delta's Target-like club, they granted me access! YMMV!