Longer Trip for Vacation

i did the high sierra trail a couple years ago and loved it. not tons of people like the jmt and a lot of awesome scenery.
it took my wife and i 5 days at a comfortable pace. the only downside the the hike is setting up a shuttle to get you to the other side of the sierras. i really loved that trip

How late in the fall do you think you want to go? Out west September vs November can mean a very big difference in weather and snow levels and temperatures which could really influence where you might like to go.

Most likely between mid-September an mid-October.

That's a tough window for the areas I'm familiar with. Just on the edge of when I'd be willing to go to the High Sierra. Not sure if that's a good month for the mountains in northern California. In Southern California that would put you at the tail end of the dry season so water would be limited, and some places will still be mighty hot.

I don't have much experience out west but that time of year Southern Utah might be one of your better bets. I went to Zion in May 2006 and it was absolutely awesome. I checked the NPS website and the weather looks pretty good in the September/October time frame. My guess is the primary concern would be water sources so you would probably have to carry a lot of water. Perhaps someone else is more familiar with the park that time of year and can give you more insights?

Steven Evans recently documented a great trip report at this thread for Zion:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=33367

The weather climate page for Zion NPS is here:
http://www.nps.gov/zion/planyourvisit/weather-and-climate.htm

Hope this helps.

Late September would be a good time for a trip to the White Mountains in New Hampshire. No bugs, weather should be nice, and fall foliage may be at or near peak. 5 days would be enough time to hike the AT from Kinsman Notch to Crawford Notch, or for an extended trip through the Pemi…

Lots of places you could go, for sure – I'm just going to discuss the Sierra as that's where I have lots of experience.
In the Sierra, Mid-September thru Mid-october is a great time to be out and a chancy time to be out. Great because the weather is often very nice – comfortable days, cool evenings and frosty mornings – and there are very few people out and about. Chancy because a storm can move in and dump rain or snow on you in large quantities.
Were I planning a Sierra trip for that time frame, I would not plan a mileage-making trip, nor a trip that took me deep into the mountains. I'd go somewhere where it's easy to bail if a storm dumps 2 feet of snow on you – which can and does happen that time of year. And I'd watch the forecast closely before the trip. If you have the schedule freedom to plan a trip for that one-month window, and then take the actual trip in the week that has the good forecast, then I can think of lots of places to go. But if you have to pick a week now, and take the weather as it comes, then I'd suggest having a few options laid out so you can adapt to the weather.

We would have to have a week planned out by mid-August or so. We would be flexible as long as it was within reach from the airport in which we booked the flights. We could go in early September if necessary.

Some places of interest (based solely on reading I have done) are:

Zion
Glacier
Yosemite
Grand Canyon
Yellowstone

Do you have any specific loops or trails in mind in these parks?

Any other suggestions?

I've been to the Grand Canyon, Zion, and Glacier on your list. That time of year you could experience heavy snow fall in Glacier so of the three I have been to I would suggest the grand canyon or Zion. You can't go wrong with either. Glacier is beautiful but it might be safer to go in July or August.

Kings Canyon NP. Rae Lakes Loop which is maybe 45miles. Then I would add side trips up toward Center Basin and other areas to get the mileage you are looking for. The only major obstacle would be Glen Pass. If you get snow turn around prior to pass and head back. Likewise if you happen to cross the pass, it's all downhill to the trailhead either direction. Fly into Fresno. About a 100 mile drive to Roads End (Trailhead)

Do you know of any goods maps for this loop?

I use the Trails Illuustrated Map by Nat Geo for Sequioa/Kings Canyon. You will see the loop at the end on Route 180. The NP website has a description of the route