We went indoor skydiving at iFLY in Union City, CA with a group outing and it was SO MUCH FUN!
It is not scary because you have a mostly solid floor, you can't see the giant jet engines and the instructors are totally helpful. We all got two times, each for a minute 30 seconds. This is plenty for a first visit. The first minute you spend figuring out how to not topple completely sideways. The second minute you figure out how to go up and down and maybe spin. In the last minute the instructor grabs you by the suit handles and takes you very high up and spins. I spent the whole spin laughing my head off-totally feels like a smooth, fast roller coaster!
I would recommend going early to watch the professionals practicing and any other newbie groups.