I've done a lot of long drives over the last several years, but not as bad as yours, usually between 2-6 hours. Here's what I do:
1. Set up a long playlist of songs. iPod, Spotify, whatever. No matter your taste in music, look for things that'll get you pumped and not put you to sleep. I've spent years crafting my various playlists for these drives, the longest being about 15 hours. I just pick the playlist for whatever mood I'm in and hit shuffle and it's non-stop songs I want to hear.
2. Podcasts are awesome. Whatever your interest, I'm sure you can find several podcasts out there you that will tickle your fancy Obviously we're on a Celticsblog, so basketball is probably up your ally, Zach Lowe, Adrian Wojnarowski, Bill Simmons are all worth checking out. And they have huge archives you can browse through. Some are topical so they might not be as interesting checking out months or years later, but others are just interviews/conversations with sports personalities. A podcast talking about the trade deadline, ya you might not want to listen to months or years after the fact, but then you have podcasts that have
Scal talking about his career and
what it was like playing with KG, those are interesting to listen to whenever.
Besides the NBA ones, I listen to podcasts on pro wrestling and vintage video game collecting. Just goes to show there's podcasts for everything. Most are usually between 1-3 hours. Easy to download too so you don't have to worry about streaming.
3. Phone calls. Have an old buddy you haven't talked to in 6 months, a grandmother that would love to hear from you? Give them a call and catch up. I save a lot of my lets-catch-up phone calls for my long drives.
My most recent 8 hour round trip went something like: spent first 2 hours catching up with a couple of friends, then the next 2 hours listening to music on the way to my destination. Then on the way back it was 1 hour of music and 3 hours of podcasts. Made the trip very bearable.