I haven't personally seen Cirque, but from what I've heard, unless you're on the very ends, there's not a bad seat in the bunch.
I'm also not sure how it works with Cirque's policies, but at most shows, they hold house seats for any performers that need tickets for friends or family. If those seats haven't been sold, they usually release them the day of the performance. I'm not sure if that's the case here, but you can call the box office and ask about it.
I just did a search for the March 2nd, 6pm performance and found a block of 4 seats (2 adults 2 kids....you didn't mention how many you'd need) in the more expensive section, so I should imagine you wouldn't have a problem.
I personally would purchase tickets now, just because I like to have everything in order and set to go before I leave.