I kind of "get" the desire to make the trip special. I go out of my way to get lie-flats sometimes PHL-LAX.
But - the simple fact is that lie-flats are very much the exception on domestic routes.
It's hard to see turning a short trip into a really long one, possibly with much greater cost (because the connections may not price out as a single trip), to get what is really not much better than lying in your recliner at home except that someone else brings you the food from the microwave. If you're taking a really long flight, or a long red-eye where you can sleep, it's a different story.
Also keep in mind that most lie-flats are designed for privacy, not for interacting with someone.
I'd definitely spend the extra $$ on a nicer room in Vegas. There are some really knock-out hotels in Vegas. My personal favorites have been Venetian and Delano, but others may have theirs to pick.