If the plane sits for 3 hours, you can hop off
During a lengthy tarmac delay in the US (upon either arrival or departure), the DOT says an airline can’t keep you on a plane for more then 3 hours (on a domestic flight) or four hours (on an international flight) without allowing you to get off if you wish. So no, playing Transformers: Age of Extinction again as in-flight entertainment isn't gonna cut it. Also, the airline is obligated to get that food and water cart running down the aisle after two hours of delay. Pass the peanuts.
If your itinerary changes, they pay the difference
Let's say you get delayed and end up not flying with your original carrier. Well, if the airline arranges alternate transportation with another carrier, it must cover all expenses and extra fees the new airline might assess. So if there's only a first-class seat available, it's yours, and it won't cost you an extra penny. Pass the champagne.
AND in that case, you get to keep your original ticket
So tell the airline to get its meaty paws off your second vacation. In essence, you get to double-dip for the annoyance of changing plans. The DOT adjusts compensation values for inflation every two years, FWIW.