What good timing for this question! We just returned yesterday from upstate NY. It's a 10-12 hour trip (depends on traffic, weather and exactly where we are going) that we drive 3-4 times a year. Our youngest is almost 2 but she's been taking the trip since she was a few months old. All 3 kids are good on the trip and pretty much anything under a 6 hour drive is a non-event for us by now. :-)
We can't do the super early or drive through the night thing. Never could, even when they were infants. We tried it once and it was the absolute worst trip we ever took. The kids usually slept good in the car as babies but the time we tried the leave super early thing it backfired... our son (who was about 11 months old at the time) never went back to sleep... at least not for 4-5 hours. He was CRANKY the rest of the day.
We leave around 6am. The car is totally packed and ready to go. We wake the kids up, change diapers and/or make 'em go to the bathroom, then put them in the car. Sometimes they fall asleep, sometimes they don't but if they don't they got a good night's sleep so it's not bad. We stop around 8am for bathroom breaks, change into clothes (they wear PJs to car) and eat breakfast. We stop every 2-3 hours. We try to keep the same routine... breakfast, play, snack, play, lunch, nap, play, dinner, play, etc. Lunch is by far the longest break and usually lasts an hour. We use the bathrooms then play (we bring a soccer ball and frisbee) at a rest area. We eat the food that isn't 'car friendly' and then finish the 'car friendly' part of lunch while driving. A 10 month old probably isn't running around but spread a blanket or something to encourage her to crawl/cruise/toddle to move around as much as possible. The kids are usually so worn out from the lunch break that they go to sleep pretty easily for naptime (except for the 6 year old... he rarely sleeps in the car).
Have the non-driver sit in the back next to your daughter to keep her busy and engaged. But also don't overlook the fact that some kids are content to just stare out the window for long stretches of time. Don't jump in just because she looks bored... a little bit of 'downtime' won't hurt.
As for toys... small board books, small toys, matchbox cars (even my girls love these), a small toddler 'purse' with stuff inside (lillianvernon.com has a good one), stickers/colorforms (colorforms stick to the window for extra fun), lacing toys (probably can't do it but like playing with the string and watching the adult do it), fabric 'busy books' and small plastic animals (some might be choking hazards but again, an adult is right there watching).
A portable DVD player for the car is great, too. They come with the straps to hang nicely on the headrest. We don't have ours on all day, though, and it's only for long trips (longer than 8 hours) so the novelty doesn't wear off. We watch a DVD after nap and once it starts to get dark out (too dark to really play with anything).
One important thing, IMO, is attitude. The trip is part of the adventure so be calm and relaxed. Something will go wrong... sick kid, spilled food, downpouring rain, need to stop more times than planned for, bad traffic, etc. Just take it in stride, be relaxed and your kids will pick up on your attitude and the trip will be enjoyable for everyone.