Vegas World suites unlock based on your highest Coin total. Once your Coin total reaches the level required to unlock a suite, the new room is unlocked and remains available to you even if your Coin total drops back down again. Once you have access to a suite, you keep it for as long as you play Vegas World. New suites do not cost you anything, they just get unlocked for free based on your Coin total.
Click where your Avatar Name is displayed to find "My Suite". Click that to enter your personal Suite.
To change your Suite, enter yours and click the "Suites" button at the bottom of the screen.
The Suite selection page will allow you to "Move In" to any suit you've unlocked. Maria has unlocked all the Suites up to Floor 31. She'll need to get her Coin total to 200 million to unlock Floor 32.
You can change which suite you're moved into as often as you like at no cost, so feel free to check them all out and see which you like best.