Another two thumbs up for the Star Trek Experience.
from me. I love it.
As Judy said, the Klingon Experience part (I think that's what they are calling it) is a motion simulator, like Star Tours at DL, if your kids can handle that without being too scared then I say it's worth it all. And the "pre-show" is out of this world!!!! Your kids would definitely love that, even if they've never seen the shows (especially Star Trek TNG....I'd suggest letting them watch a few of the episodes so they know who the crew are). (Also, as you go through the pre-show area, read what's written on the walls and look closely for the mice on the screens - best to do during a second ride - you'll see what I mean
)
There's a cool museum of sorts on the walk up to the loading area, you can go back and look at it anytime, so don't feel like you need to rush it all in at once. (You buy a day pass which is good for both of the rides as many times as you want to do them and the museum - tickets when you get there, and scan the Vegas magazines in your hotel room for discount coupons).
The Borg adventure side is a bit scarier. The main attraction is a 3-D (4-D) movie that I would equate with It's Tough to be a Bug in the type of 4-D stuff that you'll encounter. And the pre-show can be extremely scary (or extremely hysterical depending on how you feel about Borgs
). You may want to see what it's like yourself, while the kids are getting some food at Quarks, (burgers, pizza, steaks, etc.....pretty good IMHO), before taking them along for the adventure, they may get a kick out of it.
In general though, there's lots of cool stuff to see and do, even if you skip the rides and just go to Quarks, which doesn't require a ticket I think. Nothing like having a Klingon as a waiter.