Games I've started and put on hold for the longest time include the Uru expansion packs, The Dagger of Amon-Ra and The Last Express... it's been almost two years since I last played them!
When I was playing TLE, I was really obsessed with trying different things, exploring different compartments at different times, trying to hear different conversations... I must have reset the clock a few hundred times!
During the Munich-Vienna leg, I ran into some annoying technical problems with my Win98 PC, which meant putting Dagger of Amon-Ra and TLE on hold. I finally got the problems fixed, but sadly, all momentum was lost with TLE. Finally finishing all of my games on hold was supposed to be one of my adventure gaming resolutions for 2010!