10k or $100 to upgrade to first class, worth it?

Family (three of us) are heading from Orlando to Houston later this year, on the way back from Disney World. The United app is showing 10k or $100 each to upgrade to first class. The flight time is 2h:40m. Is it worth it considering the flight time? I have more than enough miles. We used 81,000 miles to book the trip. Our current seats are in Economy plus.