So what's the longest piece you've played for a concert and how long was it?
Mine is Scherzo op. 31 nr. 2 - Chopin
It's not that long (about 10 minutes), but whatever 
Don't worry, you'll get there ! Enjoyed your movie of l'isle Joyeuse(sp)

Pictures at an Exhibition/Mussorgsky. 27 minutes in 1986, 31 minutes in 2002
(getting old, or goin' ivo

)
Fantasy op.17/Schumann 29:44
Beethoven Concerto #1 op.15 35:27
Beethoven Concerto #3 op.37 about 37 minutes
Mozart Concerto in d minor K.466, about 37 minutes again
Schumann Concerto op.54 about 30 minutes
Grieg Concerto op.15 about 30 minutes
,
Concertos are long but they're segmented, you get to rest, except in the Rachmaninov 3rd, where there is hardly any rest at all. I feel that long solo pieces are more difficult than Concerti . Concerto playing is very glamorous but solo playing is more exacting (Horowitz quote).