Sorry but both the 70 degree and the 80 degree trips miss the point, IMHO.
Go for the View and adjust the temperature by the Elevation.
One other note we have normally used for trip planning is Crowds, late April May and early June along with Late/Mid September to Early/Late November just tend to be Great times to Visit the more popular areas, and generally the crowds are down, and the Weather is Great.
One more note - we (well me) love the Mountains, Streams - Rivers - Lakes - Reservoirs and Oceans - lot of spots in between that, well just really are not high on my list of Must See/Visit.
This is the first time in a long while we have traveled in the Summer - the High Season is just too Crowded for me and My Style of travel, works for some just not for me. So we will head back and wait till September to head back out, just easier and More Fun to be Spontaneous and be able to move with the Weather and away from the crowds.
SO if the Mission is just the Temperature ---- well these meet the Mission --- BUT if you want to just get out and See and Enjoy the Beauty of this Amazing Country - use the Seasons and the Elevation and you may just love it. Over the years we have found we Love it when it's a little Cooler, especially at Night.