We pre-booked our Hot Air Balloon experience with our tour provider in advance. If you go during the low season, it is possible to book while you are on safari and you might possibly get a better price. We also got picked up by a balloon company driver, however it was also possible that our regular driver could have taken us to the balloon take off (again, probably less expensive).
There were only 3 balloons taking off on our morning flight, but during the busy season, there are probably 50+. Our balloon could probably hold 16 in the basket, but there were only 2 couples including us, so they had to take some crew members to help give enough weight to navigate. This was great for us because it meant we were loaded into the front side of the basket (and the crew took pictures of us).
We did spot 3 animals that weren't seen any other time on our safaris, however you are not very close to the animals (and who knows how many we missed seeing). I also wonder how many animals get scared off if you aren't in the first few balloons. We were able to see large groups of antelope, giraffes, zebras and more, but again, not very close up. The balloon has to attain some elevation to catch the winds that direct your path of travel.
After we landed, we had a champagne toast and the crew did an awesome song and dance while we were waiting for the chase vehicle to catch up to us.
We were driven back to our breakfast spot for a huge array of food options. The setting out in the middle of the savannah was one of the highlights of this experience. The other couple in our group was celebrating a birthday, so a birthday cake was brought out at the end!
Because our accommodations were quite a ways from the hot air balloon takeoff location, we were up before 4:30 for a 6 am arrival. We were given coffee or tea (and I think there was a breakfast roll) as well as a visit to the toilet. Our balloon took off right around 6:45 am. The sunrise wasn't spectacular but the overall experience was special and something I would recommend as a once in a lifetime experience.
One negative to be prepared for is that when the balloon is initially being filled with air, they use fans to blow extra air inside (while it is still on the ground). Once we took off, every time hot air was released up into the balloon, a shower of sand fell down on our heads. Fortunately we had hats/jacket hoods, so it wasn't too bad, so be prepared!

