I will be leaving Las Vegas on Oct. 11 or 12 to head for the Grand Canyon & elsewhere in AZ.
Flying home from FLG costs $35 more than from LAS or PHX: USAir (FLG--)PHX--CLT--ILM.
Picking up an F car from Hertz at Bally's or Caesar's costs all-in:
$197 if I return to LAS; $333 to FLG; $318 to PHX.

I would like to go to Sedona for red rocks, etc. I get the idea that instead of backtracking N to FLG, it would be easier to drive S to PHX. Or is Flagstaff proper a nice place to spend a night or 2?
??s: What is interesting & how is the drive Sedona--Phoenix? Should I stay 2 nights in Phoenix metro area (probably Tue. eve.--Thu. lunch or Wed. eve. --Fri. lunch)? Or should I save money by driving back to LAS?

It probably does not matter much either way. Sedona is 45 minutes from Flagstaff. Phoenix is 2 hours from Sedona, and 2.5 from Flag. I'm surprised the flight is only $35 more - those Flag to PHX flights usually add a lot onto the trip. The airport here is a dream to get thru. You only need to show up 30 minutes before your flight and you'll still have about 24 minutes to kill.

There's plenty of places to stay here in Flag if you book a little in advance. Avoid the hotels on Lucky lane unless you like train horns late at night. Since you're coming in Oct, you might want to check out the aspen groves on Heart prairie if you're into fall colors. Sedona weather should be nice in Oct as well.

For the Flagstaff overnite, I can highly recommend Little America Inn
(http://www.littleamerica.com/flagstaff/). If you have kids that are 12 and under, I think the Grand Canyon Railroad would be the best way to go. Not only does it drop you off in the middle of the park, but you don't have to pay any park entrance fees.