Enough miles for First one-way only.. Departure or Arrival?

Greetings,

I have enough miles for an upgrade to first on one leg of my trip. Unfortunately, I did not book this flight as I am traveling with a large group of people. I should be able to upgrade to first upon check-in using miles, but I am trying to decide if it is worth sleeping well on the way or flying first on the return flight, when I am up the whole time?

Your thoughts?

Thanks,
Ronnie