Looks like you are getting some good advice, but just to back up a little - you are getting pretty far off track from your original itinerary. Please let us know what your biggest priorities are so we can help you arrange them into a doable timeline. Right now, it looks like you may sacrifice Sedona in favor of Page and Monument Valley.
If Page and Monument Valley are your priorities, I would suggest
1. Las Vegas - Flagstaff via Hoover Dam. In Flagstaff see Walnut Canyon as soon as possible after arrival, then have dinner in Downtown Flagstaff and visit Lowell Observatory in the evening. Remember, it will take you about 4 hours just to drive to Flagstaff, not counting time to pick up your luggage and rental car or stop at the Hoover Dam.
2. Up early, depart Flagstaff and drive to Grand Canyon via Highway 180 so that you enter near Grand Canyon Village, the most populated area of the park, not far from the new and very well-done Visitor Center. Visit all points east of GC Village throughout the day, exiting out the east entrance towards Page. Spend the night in Page.
3. Monument Valley (and Glen Canyon?). Spend the night in Page.
4. Depart Page in time for the first tour at Antelope Canyon. Proceed towards Flagstaff with stops at Wupatki and Sunset Crater (agree 100% - do these together) before lodging in Flagstaff that evening.
5. Return to Las Vegas. If your flight on Day 5 is not early, perhaps stop at the Hoover Dam this day instead of Day 1.
The area around Page/Monument Valley/Antelope Canyon is tricky since each attraction is relatively spread out in relation to the others. Others will be better at helping you arrange your time in that area (K-bot has lived in that area and will hopefully pop in and give some insight) How much of Glen Canyon do you want to see? You can see the dam and a small hint of the lake from the edges of Page, or you can really settle in and do an in-depth tour. Depends on your priorities, but mostly your time.