In the past, USAV Junior Nationals were the dominant championship tournament. The National Qualifiers are focused on determining which teams earn a bid to attend Nationals, along with what category a team will participate (Open, Club, American). Because it is a USA Volleyball event, there is the perceived prestige of playing for the USA Volleyball Junior National Championship.
But now, the AAU Championship has grown to a level that many VolleyFolks feel is it comparable, if not a better, National Championship event. Their selection criteria is different, and can be categorized as more 'open', with many more teams entering the tournament. AAU athletics has a long history within the USA sporting culture and because of this history, the AAU championships well respected.
In the past, USA Volleyball Junior Nationals were the dominant recruiting and year end championship tournament. But because Junior Nationals do not have a large number of teams to evaluate (because of the limited number of teams which can qualify) and they stagger the start dates of each age group, many collegiate coaches feel they not are seeing enough PSA's to justify the cost of attending when compared to the AAU Championships. The AAU tournament is very large, and only have two separate start dates for their age groups (basically younger high school and high school ages).
What your club team is considering is also what many collegiate coaches are now doing; attending both championship events. College coaches verge on panicked, especially NCAA Division I, if they are not at every possible big tournament. This is not a data backed statement, but rather my observations, but I would venture that AAU's have significantly increased the attendance by collegiate coaches, while Junior Nationals have dropped off a bit.
If I only had the budget to attend USA Volleyball Junior Nationals or AAU Championships, which was unfortunately the case all too often, I would pick AAU's. My rationale:
1. Tournament is always in Orlando, so after attending one time, you know where the two playing sites are, you know where you want to stay and you know the protocols of the tournament.
2. It is a very large and diverse tournament with teams coming from all across the USA and Puerto Rico to attend. As it is an 'open' event and is in a family vacation centered city, it is very attractive to a wide range of teams. The tournament size may result in seeing many average teams on the first day(s) of the tournament, but since it is so large, I know I can do additional evaluations on my list of PSA's, along with (hopefully) discovering some new players.
3. AAU's does a great job of customer service, from the collegiate coaches perspective, especially the Disney/ESPN facility.
4. With the Junior Volleyball Association (JVA) using AAU's as their Championship event, AAU's will have a 'guaranteed' group of elite level club teams/programs.
As for your specific concerns:
1) Yes, it is a quick turnaround from one major tournament to another, and any team risks burnout.
2) Major club tournaments are not cheap and any Championship event could easily be the 'spendiest' of the season.
3) With AAU's growing in popularity with collegiate coaches, I would not worry about attendance. If anything, I would be comfortable saying that just as many, if not more, collegiate coaches will be at AAU's.
4) The tourneys are late in the season, and club volleyball seems to grow lengthier each year. This length of season is just something which must be managed, as it is not going away.
From a recruiting perspective, the team is putting itself into the best possible position for its player's to be seen and evaluated. Some collegiate coaches look at Nationals/AAU's as the conclusion of the club volleyball season, while others will look at it as the lead in for the next season's recruiting efforts and for a great many crazy collegiate coaches, it is just two additional major recruiting tournaments because there is no end to college volleyball recruiting.
It comes down to two considerations by the VolleyFamilies - How much and how much. How much will all of this cost, and how much will the players be seen by the triple C's? If a tournament cost just a dollar, but no college coaches come watch, then from a recruiting perspective, this was a wasted dollar. For many VolleyFamilies, the cost of a championship is significant but the combination of competing against the best teams in the USA and having a large contingent of collegiate coaches in attendance is acceptable.
I would venture that if the PSA's in your club are still active in their outreach efforts, are still trying to garner more recruiting attention as opposed to making their commitment decision, then attending both events makes sense (and dollars) because collegiate coaches will not be attending another tournament en mass until 2013.
In closing, each championship tournament has its strengths and weaknesses, and each will present elite level competition and the attendance of a significant number of college coaches.