My DS 9 went to Nationals at WDW this past January. The tournaments are a blast! There are a bunch of them all across the country. The top 4 or 5 in each age division from each local event can go on to the regionals. The top 5 from the regionals are then invited to Nationals at WDW. So if teams drop out, it is no big deal, because there are so many teams that qualify. DS played U8 last year, and there were 64 teams in his division at WDW.
The biggest downfall I found was if you make it to WDW, you MUST use Kick It's
travel agency. Therefore, all the fun of finding good prices and staying wherever you want is out the window. The weather was typical for Florida in January- cold (winter coats!) for 2 days, 80 and sunny the other 2 days!
Also, it is over President's day weekend, and I was really suprised at the high crowd level, but if you are a WDW vet, you know how to make it work!
Hope your family does the tournament! We are doing 3 this summer (1/2 the team wants to go back to WDW, but I really would rather save the money for a 2 week vacation next June!) Have fun!