Las Vegas is known as the city that never sleeps yet the providers don't like to stay out late.  Is there a list of providers that make appointments midnight or later?

Sounds like you are referring to the "sudden urge" after midnight to get laid as opposed to planning for a mid-night snack in advance.  There is some discussion a page or two back about that. (See link)

Fact is, irregardless of the time of day, a vast majority of the "top shelf" ladies most likely won't respond to a  short notice request.

JMO, IMBW!

I will be vacationing there in early March.  I have no problem prebooking and keeping my schedule but would also like to go out and enjoy the nightlife.

Many providers will schedule late night appointments. The key word here is schedule. What most of us won't do is answer last minute callers. Don't call us at 2am wanting us to be there immediately.

You don't happen to provide while you're sleeping do ya'?

they are set at least 24 hours in advance

When I am in Vegas I am great with late night appointments! I don't sleep much in Vegas!  

12 hour notice will work...

I can meet you as late as 3am

me!