Vegas themed happiness.
Pick random people and give htem like $100K. But the kicker is that they have to play high limit type of games. So slots would be $750 a spin or even the $5,000 Double Double Diamond at the Wynn. I will have to be allowed to watch them gamble, and if it's a table game, even play with them. I would tell the casino to raise their table max so these people can bet higher limits than say the $5,000 table max. And because I'm the richest guy int he world, they would accommodate. Or I'd go elsehwere to a casino who would. The reason for this is that the average joe might not want to play in the high limit room, but with the regular folk at a $15 table. But bet much more. So craps table and the person has like $10K on the table, but the guy next to him is betting table min at $15.
I'd also go to average hotels like NYNY, Luxor, etc...and pick random people waiting in line to check in. Then offer them for what ever amount of time they're staying if they want to stay at Wynn, Encore, or where ever really and I'll pay for it. Plus give some $ to gamble and eat.
Finally, those youtubers I watch in Vegas who aren't millionairs, I would give them like $1 million each. So Danny the Medic, Norma Geli, JacobslifeinVegas, Vegas Must Try, etc...As a thank you.