Some states have anti-age discrimination provisions oriented at just this.

For example, in Wisconsin denying a room based on age is illegal. After some politician's kid got stuck on the road and was denied a room despite having sufficient means to cover the room charges and standard deposit, things quickly changed. And the laws usually caught up with fairness.

Provide ID that doesn't have your age.

In all seriousness, if you hold your driver's license in a "holder" and present it such that you don't need to take it out, I doubt that they will look closely, especially if you present your credit card and a frequent guest card for that property (even if the card is not useful).

Which hotel are you talking about?