My 14 year-old son and I just completed the 6-day backpacking trip from Tuolumne to Yosemite Valley (including a trip up Half Dome) with Lasting Adventures. We highly recommend both Lasting Adventures and this trip which is listed as one of their 'Guide's Choice' on their web site.
Booking the trip was straightforward on LA's website. They have several trips to choose from but they clearly spell out the itinerary (with trail maps and routes) to help you decide. LA also did a great job communicating with us leading up to the trip providing a detailed equipment list, required forms and permits needed to get into the park, etc. They were also very responsive to all questions always responding within a couple of hours.
Our guide Nicole was phenomenal. She took great care of us. Without her, we no doubt would have gotten lost in the first hour, then starved, suffered dehydration and gotten sick from exposure. In all seriousness, the meals she prepared were unbelievable whether it was the pad thai, tortellini with pesto sauce, blueberry/chocolate chip pancakes, etc. She also showed us some great spots along the trail.
On day 1, we met at 4 PM at the main parking lot in Curry Village where they provided and went over all the equipment (backpack, tent, sleeping bag, etc.). They will provide everything you need except your own personal items clothing. We then spent the first night in the Curry Village backpacker's camp in the valley.
The next morning we went by shuttle to the Tuolumne visitor center to embark on our 37+ mile journey. While that sounds like a long way, if you are reasonably fit (I'm in my early 50s), you should be able to handle it. The reward is some of the most beautiful scenery you will ever see with numerous glacier carved mountains, waterfalls and alpine lakes. Of course, the pinnacle of the trip is the opportunity to go to the top of Half Dome.
While not a relaxing vacation by any means, this was an adventure we will never forget!