Great question. Oh and if you look back through the baby section, you will find a few more posts regarding traveling with baby. ;-)
We did a 17 hour road trip to Canada to visit my family when Selin was about 3 months old. Overall it went well. To give you some perspective, it used to take just DH & I about 12-13 hours to get there but with Selin along we did have to stop more frequently. I have done the "nurse over the car seat" thing before but my state just passed back seat seatbelt laws this year so I don't think I'll be doing that with the next baby. I remember I brought along a pumped bottle of milk to give her at her first feeding to buy us some time and had a bottle warmer/car charger thing that I borrow from a friend but Selin wanted nothing to do with the bottle.
Some tips for driving:
Try to start your drive at night when baby is already asleep/sleepy, but make sure you and DH are well rested. Last summer when we were driving home from Canada, we made the mistake of hitting the road at Selin's bedtime, thinking she would fall asleep in the car and one of us could also sleep while the other drove. WRONG! She woke every hour and neither of us got much sleep. We ended up pulling into a rest area in the morning and catching an hour or two of sleep parked there. We will never hit the road with no sleep again. Going to Canada, I think we left our house around midnight and she slept until the sun came up so we got a good (quiet) start on our drive. Keep everything you need in the car with you, not in the trunk, so that if there's a diaper blowout, etc., you have everything in arms reach. Bring lots of snacks for yourself too!
Our first flight with Selin was when she was about 7 months old. We again were traveling to Canada and had a layover on the way there. I think we left in the morning so she slept most of the way there. I am still nursing so that was a great tool to have at takeoff to help with the pressure in the ears and get her to nap quickly. I usually got her situated to nurse as we were taxiing for takeoff.
We have done the long distance drive with her twice now, I have flown with her twice by myself (with layovers both times), flown once domestically with her and DH, and all three of us flew to Turkey last summer (10-12 hour non-stop flight) and every trip was never as bad as I fear it will be. We travel a lot so I now keep a packing list on my phone so I don't forget anything. I think the younger they are, the easier it is to travel because they are so portable and just want to eat and sleep! When they become toddlers, it becomes much more challenging to keep them entertained.
Again, comb the past threads for more tips on traveling with baby. I know Sarah and Ash have both written a great deal about this topic.
Jules - Happily married and Momma to DS, DD and expecting our Caboose Baby 11/24/2012