I've done Lyft codes for other events and it's worked well! I want to say you can create one code with a specific number of uses for a specific price per use (example: ABCDWed; 25 uses; $10 per use). If the ride is under the price you set, you'll only be charged for that amount, and if it's over, I think the user is charged the additional amount. FH and I were planning to go this route for our hotel guests (hotel didn't provide a shuttle but venue was only a mile away) before we changed venues and found a hotel that provided free shuttle service. If you haven't set a hotel room block yet, definitely shop around and see if any will do free shuttle service!