When I hit a jackpot, can I get free play at the casino, instead of signing a W-2G?
Nope. Sorry, but once you hit a jackpot of $1,200 or more on a gambling machine, the W-2G is automatic, stipulated by federal tax regulations.
Also, no casino, that we know of anyway, will convert your jackpot into free play.
Besides, free play wouldn't absolve you of paying taxes on your jackpot, which you seem to be implying by trying to avoid the IRS paperwork. You still owe Uncle Sam his due on free play, but when you pay and for how much comprise a complicated tax issue that's discussed at length in our book Tax Help for Gamblers by Jean Scott and Marissa Chien.
The reality is that you owe taxes on all income; if you find a nickel on the street and pick it up, you instantly owe Uncle Sam a penny. That said, not 1 in 1,000 gamblers reports his winnings that don't generate a W2-G. So given that loss of their rightful revenue, the IRS isn't about to give you a way to weasel out of reporting a $1200+ jackpot. For that matter, all comps are taxable at full retail value. So when you get that free toaster ("this week's gift"), you owe taxes on its full retail value. Likewise if you get and redeem a free room offer. I expect the IRS to slam this loophole closed very soon. If you lose $100 and earn %500 in comps (which I've done), you're liable, technically at least, for taxes on that $400 of income.