2008 Vacation Plans

As most of you know, we try to go on a big vaca on an annual basis. This year, we are looking to accommodate two big Rosales and Ochoa family events and plan a feasible itinerary around them. The Rosales family (L's maternal grandmother's side) reunion will take place Labor Day wkend, with various activities scheduled for it throughout that time. Then L's lovely cousin, Davina is getting married two weeks later. The former will be in Pueblo, CO and the latter in Denver.
Here's the tentative plan:
Drive south and catch I-70 instead of the usual barren ride thru WY. Maps.com estimates the entire drive from Layton to Pueblo as 12hrs. However, we are contemplating a brief stop at Arches NP to take some pics.

I am wavering on this b/c 1) the kids may find the trip a bit too much totalling at 14-15 hrs, 2) but we will probably have a harder time making it over there in the future, 3) gas prices (need I say more?), 4) I hate admitting to those that we've lived here in UT for 5+yrs and still haven't gone, 5) those pics would make priceless scrapbook pgs!
Reunion time. I hope others won't get too offended if we didn't attend ALL of the events. L and I are looking to sneak off to the Great Sand Dunes Natl. Mon. so the kids can sled down the dunes

and perhaps catch the cog up to Pike's Peak.

Two days of unscheduled destinations. Then off to Cheyenne to visit w/the girl who we credit for getting L and I together. I haven't yet met her darling son Andrew and her dog Sophie (hahaha). OUR Soph would get a kick out of that.
Here's another area of contention: Do we or do we not attempt an 8 hr trip to Rapid City, SD to see our other friends, the Ortegas, and see Mt. Rushmore. All factors being considered mirror those of the Arches stop. And if we opt out of this detour, what & where would we do w/the time?

Afterwards, we have reserved a stay @ the Keystone Resort thru Rocky Mountain Blue: There's no ? as to whether or not we're going here...it's too great of a deal to pass this up. Then we are headed off to Denver to attend wedding festivities (L is an usher), and back home we go!

Honestly, does this sound too much for the little runts? I'm hoping to schedule enough downtime in b/w but I suspect these guys'll be tuckered out when we get home. We have two weeks to kill and we want the kids to remember this as fondly as they do the Vegas/Disneyland/SeaWorld trip, or even the visit to L's 'rents in VA where we got to see the Luray Caverns, Colonial Williamsburg, and some days of berry picking. Anyway, would LOVE the input...
L is prob laughing at me right now and my inescapable tendencies to overthink and overplan.