I have just noticed your edit, so you certainly have time to enjoy the GC and I would recommend staying a night. On the way you could take your time, stop at the Hoover dam and even detour onto a stretch of the original route 66 from Kingman through Seligman. Down through Sedona and 'Red rock country' would be an option on the way to Palm Springs. I have not been to Palm Springs, but it is a world famous resort that competes with Vegas for tourist trade and portrays it in a more relaxed style, you will find Lot's of info using your search engine as only you can decide if it's what you are looking for. Nearby is Joshua tree NP that you could take a detour through to keep things varied. Mon night at [or near to] the canyon and a little more time there Tues Morn before heading to the Sedona area and Weds onto Palm Springs and a couple of days in San Diego could work nicely.

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