The outline of your trip looks decent, but I would encourage you not to overlook your drive times.
Your first day is doable, but factoring the time to fly across the country, stop at valley of fire for a few hours and continue to drive to Zion will be a very long day.
Many of your other drives are also based around the "late afternoon" concept, which for one makes it seems like you are treating a few hours of driving as an afterthought. The late afternoon driving means you'd be getting on the road after a day of exploring, so at the very least, make sure you are giving yourself enough time - but it's also worth noting that depending upon the temperatures, you may be better off driving in the middle of the day and doing your exploring in the morning and late afternoon when temperatures are more forgiving.
Mesa Verde to Vegas via Gallup is a full day drive all by itself (going this route also does mean you'll be skipping Monument Valley) so if you are planning to leave MV on Friday, you either won't have much any time for stopping on your way back to Vegas, or you won't be arriving back in Vegas until Saturday - which means you wouldn't really have a full day there.
