When I retired, my retirement gift to myself was a D610. I bought a 50mm lens to begin learning how to use the FF camera [I already had a 3200] but got tired of being unable to "zoom" to things far away. So I recently got a Tamron 70-300 lens. Very happy with it, but it looks like an anti-tank weapon when mounted and with its lens hood. Not exactly light either.

Might I suggest the helicopter tour? It is expensive, but the flight out to the canyon is exciting and the flight below the rim of the canyon is breathtaking. Also, returning to Las Vegas at dusk is worth the price of admission. I know you said you were staying in a different city but you might give it a thought.