We just did EMH evening at AK on Tuesday. It was nice because we got to see the park at night, and it was the only late night we did. We were at MGM for one and left early cause it was a zoo there.
We were at Rafiki's Planet Watch up to regular park closing - 7:00 pm. Then we went over to Kahli and had about a 15-20 minute wait (did baby swap) so took a little time for both groups to ride. Then went over to Dinoland and did Triceratops spin with about a 3-5 minute wait. Primaevil whirl was down - not sure how long, but a lot of people were there just staning around and heading over to do Dinosaur so I think that had line, but not sure how long.
We left AK around 8:50 and there were lots of people there. We got to the POP bus stop and had to wait for 3 buses, which was more than for AK around closing usually. Howevere, the poor All-Stars bus line was backed up to where the AK bus stop sign (the one saying which stop is which resort) was. It was crazy.
Overall AK late night was nice, but I wouldn't say there were walk-ons and no crowds. It must depend on the time of year. I love AK on a regular closing night, then it really clears out and you can catch a late safari right before 7:00 or walk on the trails with no crowds.
Not too many attractions opened - Kahli, All of Dinoland, an extra Tarzan Rocks at 8:15, an extra Festival of the lion king at 7:30, Tough to be a bug, and the last safari ran at 7:30 pm. Most snack carts were closed, and a few counter service(Pizzafari & Restaurantosaurus) were opened but I don't know how late.
To me it seemed like the late nights were where everybody went. I'm glad we did a late night at AK, but I'm also glad we avoided the other ones.