Aug.23, 2014:
We used Southwest for our air travel.  We were even able to get one STL-LAS trip free with reward miles.  That turned out to be the most expensive fare, even though I kept checking all the way up until  our flights.  The other flights did go down a bit and I was able to re book them and have a credit for a future flight on SW.  Gotta love SW and their no fee changes and no luggage fee.  We did just have carry on luggage, but checked it most of the time anyway.  We don't often fly into LAS, so I was quite intrigued by the views from the plane over what I assume were parts of the Grand Canyon.

Our car rental was with Budget.  Got the best deal from them for a full sized car for $155 including taxes and fees, plus we're Fastbreak members, so getting our car in a busy place like LAS was a breeze.  We found the shuttle to the off airport rental car complex and went straight to the garage, bypassing the Budget counter.  In the garage, the Fastbreak booth had our car ready and we were on our way to Utah in a few short minutes.  With Garmin plugged in, we quickly found I-15 and were heading north out of Vegas by about 4pm.
I had read that Valley of Fire was just off I-15 on our way to Utah, so we made about a 2 hour detour there.  It gets its name from red sandstone formations formed from great shifting sand dunes during the age of dinosaurs.  There was a $10 fee charged upon entering, but it was well worth it.  There are about 20 miles of paved roadway in the park.  There are also lots of hiking paths.  Since we were in a bit of a hurry, we didn't do any of the hiking, just stopped at the visitor center and at several of the trail heads to take pictures.

 View of the visitors' center from the road

Rainbow Vista trailhead

 rocks along the road

driving up towards White Domes

White Domes

heading back down from White Domes

 Seven Sisters pull out.

 Beehives pull out, although this looks like a bunny to me!

Then we headed back to I-15 and continued on towards Utah.  We arrived into Utah shortly after sunset.

We were getting a bit concerned with where Garmin was taking us once we got to St. George.  The address I had for the resort didn't come up on Garmin (I should know to check that out ahead of time by now!), so I used the street address without the W. added to it.  But after coming to a construction area and driving through it a couple miles, there popped up St. George Worldmark.  We used Wyndham points for our RCI exchange.  We're Worldmark owners, too, but prefer to use those points for Maui.  The St. George Worldmark was great!  We had a 2 bedroom unit.  Didn't need the extra bedroom, but the 2 bedroom units always have a larger living area and an extra bathroom, so we were very comfortable.
The main living area.  Front door just past the Murphy bed on the right.  The 2 bedrooms on either side at the end of the hall.

From foyer looking left. (Murphy bed behind the doors on the left).

 master bedroom

our patio

 The pool by our unit.  Jacuzzi in the back, kiddie pool out of sight to my left.  I thoroughly enjoyed the pool and jacuzzi several times.

 This is looking like it'll be a great vacation!