Oh, you will be spoilt for choice when you go in August. Here is a run down from my perspective:
Tarzan - this show has been dark for the last 2 years, but ran for nearly 10 years to huge crowds and acclaim. It is my fav show to grace the stage at any theme park (only rivalled by Aladdin in DCA and maybe the Finding Nemo Musical in DAK). It uses circus arts and the wonderful sound track to tell the story of Tarzan. The ariel ballet between Tarzan and Jane is pure magic, and makes me feel all goooey inside.
Moteurs Action - this show is marmite, people either love it or hate it. It shows you behind the scenes of how they film motorcycle and car stunts, and was designed by Remy Julienne who designed stunts for many James Bond movies, the original Italian Job and Indiana Jones and the Last Crusade. Awesome
Cinemagique - if you love cinema, this is a must. It has won international awards for good reason. Part film, part special effects. It is a must sea IMHO.
Buffalo Bill's Wild West Show (chargeable dinner show worth every penny, and the best dinner show Disney has done anywhere IMHO). 90 minutes of horse stunts, native american dancing, real buffalo all while you enjoy a BBQ dinner and drink or coke. There is a souvenir cowboy hat to take home!
Stitch Live - cute especially if you have little ones, the audience talk with Stitch.
Those for me are the must sees. The others include:
Animagique - a blacklit puppet/character show where Donald disobey's Mickey and ends up travelling through the Lion King, Jungle Book, Dumbo and the Little Mermaid. My kids adore this one.
Art of Animation - a 4 part attraction, the first is exploring the early animation forms, the second is a film presentation of the Disney classics in different languages, the third is an animator and mushu explaining how characters are developed, and the forth is a hands on area where you can learn to draw a character, colour animation, add sound effects and record dialogue.
Captain Eo in Discoveryland is a mixed bag. I love it for nostalgia sake as I was at the grand opening at
Disneyland in 1985 when digital 3D was very new. And enjoyed it at DLP's grand opening in 1992. So there is a lot of nostalgia for me. The script and acting are poor, but it is a great 15 minute Michael Jackson music video in 3D, done by George Lucas and Francis Ford Coppola. Mileage may vary.
There will be a new show on the hub in DLP, but no one has seen it yet. This year's was ok. Not a must, but ok IMHO.
If you have any under 5's, Playhouse Disney Live is excellent for them.
Hope that helps.