In researching Yosemite I'm now super excited about it as I think it'll be one of, if not the highlight of the trip. A few horror stories about how busy the park can get, but I'm hopeful that because we're going very slightly outside of peak-season it might not be quite so bad (ironically before the trip got postponed we were going in August 2018, which might have been way worse!)
I'm just coming to the end of a 12-day stay in Yosemite with the family (tomorrow is our last day
) after a few days in San Fran. We have been staying in Yosemite West, which is about 25-30 mins closer to the valley than you will be in Fish Camp.
Most of the larger waterfalls are still flowing pretty well, but it's getting to the point in the year where everything is starting to dry up. Mirror lake was well past its best, although it was still a nice walk around it - particularly at the top end where we spent a while having a dip in the river (flippin freezing mind...). The Mist Trail is great - but I'd suggest going up rather than down it as it is very steep and slippy in places. We went up the Mist trail and up further through 'little Yosemite Valley' towards Half Dome (the kids did the whole Half Dome trail/climb but our old knees/lungs would never manage it all
) and then came back down via the lower section of the John Muir trail - but that took us a solid 8-9 hours! The full Half Dome trail/climb took the kids nearly 12 hours
Dog Lake up near to Tuolumne Meadows, together with Lembert Dome on the way back down was a highlight for us, but it's a good few hours to walk that loop and enjoy the lake so you may well struggle to fit that in on your travel day into the park, and it will be 2 hours each way to get back up there from Fish Camp.
Parking in the valley itself can be a nightmare - particularly at the top end near Curry Village and the so I'd highly recommend getting up early and getting into the valley before it gets too busy. Also, don't underestimate just how tough some of the trails can be in terms of what you can realistically expect to fit into 3 days, especially at 6000-8000ft of altitude (although I'm sure you are a good deal younger and fitter than me and the mrs!)
Anyway - here's a few photos from the last few days to whet your appetite
McGurk Meadows:
Mirror Lake:
Dog Lake:
Yosemite Valley itself: