Ann,
To add to what Bob says my sory is similar, I did Golden West in 2010 (awsome holiday you'll love it) and the trip to the Grand Canyon was great but in hindsight a waste of money.
Why ? Not that it wasn't worhwhile but the following year I did the "Parks & Canyons" which goes from Phoenix to Vegas and we visited the GC on route and had option of the helicopter again.
Also visited the GC on Route 66 last year although thats only a photo chance as you don't have time to do much else.
Also like Bob (we'll meet one of these trips) I'm doing National Parks, Mount Rushmore, LBH this year and we stay over at the Canyon which is great, give me chance to walk so far into the canyon along the mule trail i hope (would imagine others that have not been will do the helicopter so will have time to fill in).
Vegas is a fair distance west of the GC hence the expensive flight to get there and too far out the way for the Golden west hol to visit on route as you arrive in Vegas from he opposite direction, much better to visit on a holiday that actually goes to the canyon.
Mick