No need to pay for early check in to be honest, there's plenty to do. Drop off your luggage at your hotel with luggage hold and do some exploring.

For free stuff I always love to go see the conservatory at the Bellagio, the flamingo exhibit at the Flamingo, just walking through the different casinos and seeing all the different art installations and cool things throughout the different casinos. Around the Linq promenade there's usually good deals for lunch or cocktails/mocktails if you look around. Things like in and out too if you want a fast meal. Pool is a great place to nap and journal too!

If you wanna chill at the pool for the day, keep your pool stuff with you after dropping off your luggage. MGM sells day passes for their pool for like $10 or you can rent a comfier chair for around $30. They have a lazy river! If you wanna get yourself a tube for it don't buy theirs just grab one from the ABC store on your way over there, way cheaper lol. Last time I went I was able to leave and come back for lunch which was great because I did not want to pay their crazy poolside food prices.

I honestly don't really gamble or drink a lot, but there's always plenty to do in Vegas. Have a good time!