Switch to later flight
 

I'm sitting in the DTW WC and I'm thinking about switching to the flight leaving at 1530 instead of 1230 for LAS becuase it still has open F seats (like 6) and I am going to miss my upgrade and not even get an exit row on the 1230 flight to vegas.

So I'm curious if you have any experience in doing this. Will there be a fee charged? does it just depend on who you talk to? Can I still get a Battlefield upgrade if I change the flight?

Thanks (sorry my search isn't working right now)