You’ll have a blast in Yosemite!! We took our slightly younger kids there about 3 years ago. We stayed in the park in early May so the visitor numbers were MUCH less than what you’ll experience in July, but there is a great free shuttle bus that you can jump on and off all over the valley floor so you don’t have to worry about driving.
Walk the Mist Trail. You have an option of a 3 mike round trip hike or 7 miler depending on how far you want to go. Vernal and Nevada Falls.
Walk to the bottom of Yosemite Falls. It’s super short, but sweet. You can also go to the top of both upper and lower falls, but those are long long hikes that would probably knock the kids out of wanting to do any more!
Walk to the base of Bridalveil Falls. It’s just over a mile round trip but it’s pretty.
Make a reservation NOW to eat either breakfast or dinner (dinner is very pricey) at the Ahwahnee Hotel. Get there at least an hour before your reservation to hang out and walk the grounds, check out the monstrous fireplaces, etc. The architecture in the great room/dining room are phenomenal and you just might see bears walking by the giant floor to ceiling windows. (One of my favorite memories as a kid after walking there with my dad for hot chocolate one morning. Something I’ll never forget). And the food is amazing. (Edit: There is a dress code for dinner. If you go that route make sure you have proper attire - totally worth it).
Get ice cream at Curry Village. Go swimming. Play in the river (in a safe spot of course), have a picnic in the meadow in the middle of the park. Bring binoculars so you can try to spot climbers on El Cap.
And lastly, drive up to Glacier Point. Or if you are very adventurous, plan ahead, book your seats on a tour bus, and hike the 4 Mile Trail either from the bottom or the top (then you shuttle it the reverse direction). We wanted to do that but the weather was bad and kids a bit too young.
Here’s a good website that describes a lot of Yosemite hikes.
https://www.yosemitehikes.com You’ll find with the kids that there are a lot of shorter hikes you can do and plenty to keep them occupied when not hiking. There are also tons of trails on the valley floor that have nothing to do with “hiking”. Just walking.
Do the horseback ride tour. We did that when I was a kid a few times. Super fun even for youngsters with zero riding experience.
Rent bikes at Curry Village to skip the bus or driving.
Have them become Junior Rangers (ask at the first Ranger Station you see for info). They will learn a lot about the park, get sworn in and get a badge if they can complete the required info. My boys are obsessed with this at all the NP’s and Monuments we go to.
Have a blast! Yosemite is amazing - crowded or not. Just don’t be in a hurry to get anywhere because in July it isn’t going to happen!
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Harry: "I expected the Rocky Mountains to be a little rockier than this."
Loyd: "I was thinking the same thing. That John Denver's full of shit, man."