I did the JMT last year (2018) NOBO with my wife and kids (8 & 11). We took 25 days which seemed a really nice pace.
If you go NOBO, the permits are approximately a million times easier to handle. No Donohue pass limit, apply online real-time for the date you want, and start at any of cottonwood pass, cottonwood lakes or Whitney trail.
MTR was a great, simple resupply venue with fantastic hiker boxes and friendly staff.
We used Sequoia Kings Pack Train to resupply us over Kearsarge. This was a mistake, I'd never use them again. We agreed an 8am resupply, which was going to involve the packer coming in the night before, overnighting at Charlotte Lake, and meeting us first thing for resupply- this was agreed, contracted and paid for.
Instead, without out knowledge, our packer was reassigned to take a spot trip into Kearsarge lakes, (much more lucrative I'm sure) and didn't meet us till 3.30pm, at which point we were getting ready to pack up and walk out. When it hadn't arrived by 9am I managed to exchange inreach messages with SKPT where the owner assured me my package would be with me by midday... When it hadn't arrived and I was starting to get worried, she stopped responding to messages. Some of her messages were as ridiculous as (at about 12.30) "you should be able to see the packer coming down the trail towards you now" - at this point we were on the JMT, but the packer was still 5 miles away around Kearsarge pass. When the packer arrived, I discovered she had no way of communicating with base, so they were just making up a story about where she was.
The promised refund never happened either.
My particular frustration was that my original plan had been to leave a resupply in the boxes at the trailhead and run out and back to collect it, but we decided it was better to save a day. I could have run out and back long before the pack train ever arrived.
