Unfortunately, the WT seats do not offer power ports for laptops.
Gleaned from Apple, here is a summary of max playback durations for the current line up of models:
iPod Touch (8/16GB models):
Music: approx 22 hours playtime
Video: approx 5 hours playtime
iPod Classic (80/160GB models):
Music: approx 30 hours playtime
Video: approx 5 hours playtime
iPod Nano (4/8GB models):
Music: approx 24 hours playtime
Video: approx 5 hours playtime
iPod Shuffle (1GB):
Music: approx 12 hours playtime
You can be assured of more precise feedback and advice over on the Travel Technology forum. To save you reposting, I shall move this thread over there.