I was just looking at the tickets the other day at the Chantilly Costco! I was coming here to confirm if they are valid for any 3 days until 2014! I need one day, maybe 2 for next March/April. Trying to decide whether to spend the extra money to get these tickets, on the likelihood that we'll be back again before they expire, or just buy the 1 day tickets...
We were just there in August for 2 days. I wish I'd found these tickets before that trip, because we had bought 3 day tickets for that trip (from another source) - and the 3rd day expired when we didn't use within 14 days.
As far as your question on the kids. in August, we had to write their names on the tickets, but they didn't show any ID or anything.