My first recommendation is to check out the "What should I pack for a road trip in the USA" link at the above right under "Top Questions About Road Trips" section.
Personally, I'm of the mindset of one suitcase per person--you pack it, you lug it--approach.
So if your daughter wants to bring a suitcase the size of a small house, make a deal with her that she packs it, handles it every day of the trip, and does so without complaint. :-)
That said, if I'm going to be in a different hotel every night, I generally will carry along a small backpack or bag that I use each night. I'll pull out a set of clean clothes and toiletries for the next day out of my suitcase in the trunk, put them in the back pack, and take them up to the room, leaving my suitcase in the locked trunk. Any valuables (camera, laptop, etc.) always come to the room with me. (With an SUV, it may be more difficult to hide suitcases left inside, so you may want to bring them in to avoid tempting any would-be thieves.)
The next morning, I take my dirty clothes put them in the backpack, carry them down to the car, and put them in a dirty clothes laundry bag in the trunk. That way, they stay separate from the clean clothes and are easily gathered for laundry day, whether on the road or on return home.
Regardless of how carefully you think through your packing plan, I can pretty much guarantee that you'll be changing it your first night or two on the road, then you'll settle into a routine that works best.
A couple of other geeky packing / road tripping tips:
- I love Ziploc freezer bags for my electronics. I have one for my GPS unit, cable, and mount; one for my cell phone charger and power adapters (when traveling to Europe); and one for my camera (spare battery, charger, cables). Of course, I label the bags with the contents.
- I use the black "Bulldog" spring clips to keep the pages of my atlas open to where I need them to be (yes, I still bring a paper atlas even with my GPS).
- I use a plastic garbage bag from the grocery store to put the garbage that I accumulate through the day into it.
- I always have a couple of bottles of water with me in case of breakdown, especially if I'm traveling when it's hot or when going through remote areas.
Hope that helps give you some ideas.
Edited: 1:10 pm, April 22, 2013