Stronger has been certified Platinum.  
https://twitter.com/AmericanIdol/status/248924366824431616/photo/1

S8 had 5 more shows that added in to the totals so it is not at all accurate to use total tickets sold in any equation for comparison/trends. Looking instead at average attendance per show eliminates that variable between seasons.

Also, S10 had 15 more sold out shows than S8 even though they had less total shows scheduled (and who’s to know if the 5 extra shows would’ve also been sold out?). However, I don’t mean to linger on this stat b/c the # shows sold out only interest me in how they effect the attendance numbers for those particular shows. That number really is primarily an indication of how well TPTB pre-scheduled the tours.   

I really don’t want to give the impression that I’m trying to prove S10 was “the greatest season ever.” I’m not at all invested in Idol in any way, and certainly not enough to care which season is the best/worst. I just find it interesting that there really hasn’t been a marked trend in Idol tour interest negatively or positively over the last 10 years. I’m now curious to know if the ratings show a similar pattern  to correlate with the attendance numbers. I had assumed the ratings were showing a steady decline with a small bump up in S10 but that was just a wild guess.  

From Idol Chatter:

Idol albums

Carrie Underwood, Blown Away (15,000, -49%, 794,000) (#24 Billboard
Kelly Clarkson, Stronger (4,000, -14%, 929,000) (#89 BB200)
Phillip Phillips, American Idol (3,000, -13%, 80,000) (#156 BB200)
Mandisa, What If We Were Real (2,000, +41%, 212,000) (#170 BB200)
Bucky Covington, Good Guys (2,000, debut, 2,000) (#178 BB200)
Carrie Underwood, Some Hearts (2,000, -3%, 7.235 million)
Scotty McCreery, Clear as Day (2,000, -10%, 1.111 million)
Carrie Underwood, Play On (1,000, -4%, 2.136 million)
Skylar Laine, American Idol (1,000, -13%, 32,000)
Casey James, Casey James (1,000, +7%, 51,000)
Carrie Underwood, Carnival Ride (1,000, +3%, 3.28 million)
Casey Abrams, Casey Abrams (less than 1,000, +33%, 15,000)
Hollie Cavanagh, American Idol (less than 1,000, -15%, 13,000)

Idol track downloads

Phillip Phillips, Home (101,000, -9%, 1.653 million)
Carrie Underwood, Blown Away (67,000, -9%, 804,000)
Nicki Minaj, Pound the Alarm (59,000, -13%, 530,000)
Kelly Clarkson, Dark Side (28,000, -18%, 519,000)
Nicki Minaj/Cassie, The Boys (25,000, debut, 25,000)
Kelly Clarkson, Stronger (What Doesn’t Kill You) (17,000, -9%, 3.765 million)
Nicki Minaj, Starships (16,000, -13%, 2.696 million)
Nicki Minaj, Starships (12,000, -16%, 1.002 million)
Carrie Underwood, Good Girl (10,000, +5%, 1.339 million)
Casey James, Crying on a Suitcase (9,000, +32%, 53,000)
Mandisa feat. TobyMac, Good Morning (5,000, -2%, 196,000)
Brad Paisley/Carrie Underwood, Remind Me (5,000, -6%, 1.644 million)
Carrie Underwood, Before He Cheats (5,000, +9%, 3.569 million)
Jason Aldean/Kelly Clarkson, Don’t You Wanna Stay (4,000, -14%, 2.163 million)
Carrie Underwood, How Great Thou Art (2,000, +1%, 362,000)
Jason Castro, Only a Mountain (1,000, 0 change, 12,000)
Jason Castro, Hallelujah [Album Version] (1,000, +114%, 106,000)
Mandisa, Stronger (1,000, -13%, 206,000)

Season 5 may have had a successful tour, but it was only 1 of 2 Seasons whose winner did not sell Platinum.  The other was Season 9.

You forgot season 8. But season 5 does has the highest number of alumni who went gold or platinum (Taylor, Elliott, Chris, Kellie) and another 3 who went over 200,000 sales: (Kat, Bucky, Mandisa). I really believe that season was the apex of American Idol as a force in pop culture.

Yes, good point about S8 having more shows. If that is taken into account by projecting that S10 may have drawn according to its average attendance (5 X 8,589 = 42,045), then the difference is only 37,772, which when divided among 24 shows = 1,574. I still think that S8 would have a higher total attendance, especially when its 8 sold out shows are considered and that it had a higher average attendance than S10, but at this point, it’s all speculation that can’t be proven one way or the other.

I think that commercially speaking, S9 was by far the worst season for Idol. However, I think that everyone has his/her own opinion on the ranking of the seasons from best to worst that depend on their favorites (or lack of them) during each season and how entertained they were by the cast, in general. So for me, S9 isn’t ranked last because I liked Crystal, but S10 and S11 are ranked lower than S9 because of less entertainment value for me personally. 

I checked out Taylor Hicks album after his Idol win and it is RIAA certified Platinum.  At least that is what I have read.  True or False?

Only 11 boxscores reported (Season 9).  What does this mean?  Thank you. I really liked Season 9 and thoroughly enjoyed the concert!