Everyone has their own limit for how far/how long they can drive in a day. If you're used to driving a lot, are going with someone you get along with nicely, and are willing to push it, definitely go as far as possible. I'm a huge fan of just getting in the car solo with a lot of water, some Diet Cokes, a box of NutriGrain bars and a couple packs of smokes and just going for 14 hours, stopping for five minutes about every 90 minutes to use the restroom, stretch, and walk around.

Having someone to share the driving helps, but not as much as people think, imho. The passenger is still in the car, still getting highway hypnotized, and getting just as stiff and tired as the driver. The passenger can nap, but unless they get four or five hours in a row, they'll still get sleepy when it gets dark at about the same time as the driver.

I don't recommend setting distance goals every day. If you hit traffic or bad weather you'll feel obligated to keep going even when you're tired and stressed. This leads to accidents and fights. Drive as far and long as you can, then stop when you need to for rest, and before you need to for the night. Assuming you get a fairly early start, you'll still put in about 10 hours behind the wheel during daylight and should get you there in 3-4 days.

I prefer to do solo treks, but when travelling with a friend, I normally have a pretty good strategy. I wake up at about 0500 with ease, unlike most of my friends. I'll get up, fill up on gas, fluids and snacks, shower, wake up my friend and bundle him/her into the car and onto the road by 0530-0545. He/she will normally sleep soundly for another two to three hours. I drive through to early lunchtime, then turn the wheel over so I can close my eyes and maybe sleep for 3.5 hours or so (enough time for a helpful nap). I then take over again and drive through dinner, then let him/her drive until they are tired. I end up doing 2/3 of the driving, which I prefer anyway, and we're both a little fresher at the end of the day while still getting 14-16 hours of driving in. With three people it's even easier: everyone gets a 1.5 hour shift behind the wheel and a 3 hour chance to stretch out on the back seat (3 in the back while 1 and 2 take their shifts, 2 in the back while 3 and 1 take their shifts, 1 in the back while 2 and 3 take their shifts).

Best group road trip I ever did, though, was me driving a mini-van from Tampa Bay to Washington, DC with six other people. I did all the driving because they bet me $10-$20 each I wouldn't make it all the way, they shared a couple cases of beer. It was easy to stay awake laughing at them being idiots, while time flew for them. 14 hours later we're home, safe and sound and happy (and me over $100 richer ).