The Echo Show is an Alexa assistant with a display, and I think the killer app for this device is game shows like Jeopardy where Alexa serves as the host. Alexa can display the game, narrate questions, listen for answers, and keep track of score.
Trivia games like Jeopardy, Who Wants To Be A Millionaire, You Don’t Know Jack, and Trivial Pursuit would be the most fun use of Alexa’s interactive abilities. Other game shows like Wheel of Fortune and Price is Right could be done but they wouldn’t be as engaging to play in my opinion.
Some additional props may be needed. For Jeopardy, 3 buzzer devices are needed, all with distinct sounds so Alexa can tell who is buzzing and who buzzed first. For Final Jeopardy, participants would write down their answers on paper and read them aloud when called upon by Alexa.
Alexa recently added a Skyrim app, which turned the assistant into a Dungeon Master of sorts, so she is willing to play along with users. Hopefully she can take the next step and turn millions of people into contestants.