I agree with all that's been said.
@DaveNW move this to the tippy-top of your list.
@Beachclubmum wasn't that amazing to see it without people?
@queenofthehive just like you, the memories are the best.
I grew up in a non-traveling family (my first ever away-from-home vacation was my honeymoon) so I didn't see Yosemite until I was 30 and for the life of me, couldn't figure out why we hadn't visited when I was a kid. Things were even a bit crowded when we went in the early 90's so we tent camped outside of the valley in Crane Flat. There we had a favorite campsite and stayed there a few times. The biggest selling feature was the "fairy circle" in the woods behind the campsite. My kids called it that, not really sure why, but looking back on it now that is the sweetest memory.
My favorite trips were made in April - low crowds and sometimes snow. When we went in April we either rented an RV or stayed at the lodge. One year were were bicycling through the valley and it went from cold to snowing in the blink of an eye, which was just beautiful. To get out of the snow and to warm up, we spent the afternoon in the cafeteria playing Uno with our youngest daughter, watching the snow fall outside.
Another April trip in the snow was the coldest we have ever been while camping. Lows in the 20's highs, in the 40's. We were with friends so we really didn't want to spend the week inside our respective RV's so we used our pop-up over the fire so that we could sit around the fire without getting wet. I don't regret that decision at all but it did ruin that popup. When we went to pop it up a few months later at a lacrosse tournament, you could smell the campfire smell from 50 yards away and once popped up you could see the hundreds of tiny holes from the embers.
My other favorite thing about April are the dogwood flowers. For me nothing says "spring" like seeing the dogwoods.
My middle daughter loves it so much that she and my SIL got married in the valley in 2016, in the shadow of El Capitan. So yes, many wonderful memories in that valley for our family - and a million other families I am sure.