Done both and would go for Grand Canyon without a doubt. Views are just stunning and you can walk down into the canyon. Yosemite is also stunning but I wouldn’t go back as everyone wants to drive everywhere rather than get out and walk so it’s literally like sitting in a parking lot as you try to get in or out of the park.

Very hard to choose between Yosemite and Grand Canyon. Whichever you choose you won't be disappointed!

I'd probably base it on what your priorities are for the rest of the trip and see which one fits into the schedule best. If you are doing PCH then its Yosemite, if you are doing Vegas and into the desert then Grand Canyon works best.

We have done two West Coast Trips. In 2013 we flew in and out of SF and did a trip down PCH then back inland up to Yosemite. Yosemite and PCH were the highlights but doing that in 2 weeks we did find we were moving on too often. In hindsight it would have been better flying into SF and out of LA or vice versa.

This year we flew into LA and drove to Vegas via Death Valley, then on to Grand Canyon, Monument Valley, Zion and across to Newport Beach before flying back.

If I had to pick my favorite of the two trips I would say this years. Zion especially was amazing, but Grand Canyon & Monument Valley were not far behind.

The 2013 trip was great too, but the weather on the coast was not so great and there was not the range of scenery we saw this year. We drove more miles this year, but it didn't feel that way.

Having waffled on I guess my advice is don't try to pack too much in and if PCH is a definite then combine that with Yosemite, and do Grand Canyon and beyond another year!