To be honest you don't have time to visit Havasu Falls as it's a difficult and time consuming place to get to. You probably need to half your mileage and decide what's more important and then decide whether Denver or Vegas would be the best start point.

Example Denver; RMNP, Colorado National Monument, Arches and Canyonlands, Mesa Verde, (maybe a detour to Four corners/Monument valley before Mesa V.) drive the 'Million dollar Highway' (US550) through Silverton and Ouray, Black canyon, Currecanti National Recreation area (US50) Great Sand dunes(?) Pikes Peak and Garden of the Gods back to Denver.

Example Las Vegas. Zion NP, Bryce canyon NP, Capital Reef NP, Arches and Canyonlands, Monument valley, Page, Grand canyon, Sedona and back to Vegas.

We all start out by listing way to much to see and then it's a case of trimming back. You can attempt to see too much and end up actually seeing very little of these amazing places. There are also many other options, as aid the above are just a couple of examples that will keep you busy but at least have time to enjoy.