One nice thing about this type of itinerary is that they might have a
favorable Business Class option available, at least on the long haul
segments.

A good point -- I just spent a total of 14 hours on airplanes in the
course of a 22-hour-long (body time) travel day, in coach and most of
it on pretty full flights, which is quite common now that a lot of
airlines have cut back their capacity to meet lowered demand.
Fortunately most of this was on Air France, one of the airlines that
still act as though they appreciate your business, but nonetheless
the people forward of the curtain seemed to be having a better time.

By sticking to one alliance as much as you can, you also concentrate
your frequent-flyer miles instead of spreading them among several
places where you might never accumulate quite enough to use.

Something worth mentioning about the Vegas-LA (or really, Vegas-
anywhere) bit of the itinerary is that it has some of the most
flexible flight options. You can even take a bus to any number of
points in the LA area if you're yearning for a ground-level view of
the desert (well, okay, probably looks a lot like your own desert...)
and a better or at least different chance to meet people. Getting
you to and from Vegas, either on a planned basis or on the spur of the
moment (before your luck runs cold or the girl changes her mind about
marrying you or whatever), is a big business in the US, and there are
a lot of choices. Even a one-way car rental might not prove to be
completely silly if you'd rather try that.

Alas, I don't think the train service lasted long (1999-2001?) and
more-recent talk about a futuristic high-speed train was sidetracked
when the economy derailed. Amtrak offers some ability to book you
on that route, but AFAIK they just sell the ticket as part of their
overall service, and the actual trip occurs on a bus.

--Joe