I’ve had similar thoughts, not as a entrepreneur, but as a way to squander the lottery money on one epic party, that starts in Seattle and ends 32 hours later in LA.
A really enterprising transit agency (an oxymoron there) would create The Party Bus and promote the hell out of it. Rip out all the seats and put in couches. Special lighting. Use your imagination.
Edited to add: you can, of course, also rent the modern busses and streetcars. And even subway cars!
It's pretty much only young people that hire them.