This is a really common question, and I'm still asking OTHERS the same about their extended travel! Today I received an e-mail asking how and when we started traveling with our kids, and how we manage it, etc. Thought I'd post my response here for anyone to see.
First of all, we started getting out and about when my daughter was 4 months old with hikes and parks and other baby friendly outings in SLO County. From that arose a book, "Best Family Adventures: San Luis Obispo County." The day trips certainly built her stamina in the car seat, and taught us how to work with her in local travels before trying to make a big trip.
We took our first big road trip when our oldest daughter was 2 (to Colorado). We opted to drive at night in hopes she would sleep. Right! She was awake until about 2 a.m. having the time of her life in the back seat with random toys, lights out the window, singing along. She fell asleep at the Nevada/California state line! So...don't count on that!
The next time we drove to Colorado was when our oldest had just turned 4 and the littlest was almost 2. We decided to take the overnight route since DH was working graveyards and used to staying up all day. That worked pretty well.
When the girls were 2 1/2 and 5, I took my first really extended road trip with them: 3,000+ mile tour of Washington and Oregon. This was the first long trip I did on my own, and though it was a memorable trip, the girls remember so little of it I think that, if I were to do it again, I might wait a year or two. Then again, they brought home a lot from the trip, though, that they'll be able to use the rest of their lives. Chiefly, confidence. They both helped set up and take down camp each day, and each had chores. By the time we got home, my meek 5 year old who never did much on her own without asking for help was dragging her play tent out of the playroom closet and setting it up in the backyard, giving instruction to her sister all the while, without a single request for help from me. THIS is the kind of thing travel has done for my kids, in addition to giving them a more expansive understanding of the world in which they live. They may not remember WHERE they learned these facts of life on Earth, but they remember the information and continue to build upon it.
Affording the trips is another matter. First and most importantly, I'll make it clear that I live, at this point, through the good graces of my husband. He does the full-time, shelter-providing, food-gathering work. Any additional money I bring in with, say, book sales (hint-hint) or freelance journalism is spent on extras like travel, holiday gifts, birthday gifts...extras. So, there's some saving involved.
We also travel on a budget. We travel by tent because it's the cheapest way to go (unless you count the freebie "camping" in Wal-Mart parking lots for self-contained vehicles: trailers, campers, RVs...but then you have the terrible gas mileage, so it's probably a wash). There's free camping available in some forests, BLM land and on U.S. Corps of Engineers property. There is also low-cost camping on those lands. Then there's the full-rate campgrounds, but they can include pools, showers and laundry, so they're good to mix in as needed (or desired). Travel by tent is also the most flexible because we can get our little minivan just about anywhere while driving the behemoth RV we all envy would be a nightmare in so many places. We also pack our food and shop along the way, limiting our restaurant dining as much as possible. (It's POSSIBLE to omit dining out entirely, but realistically it's incredibly nice to have someone serve you when you've traveled all day and set up camp and torn down camp and done it all again day in, day out. Plus, it's fun to try out local favorites. I steer clear of chains as much as possible when I travel, which, when I travel without DH, means we don't do the chain thing at all.)
Then there's the matter of time. Who has this kind of time off work? Well, no one I know. More often than not we travel without DH. He's not interested in road trips per se, but he knows I love to drive, to explore, to enjoy adventures, so sends us off with hugs, kisses and best wishes. This also means that he doesn't have to use up his vacation time doing things in which he's not especially interested. (Oh, and he get the house, and his life, back to himself for awhile.) He saves up his vacation for those adventures which pique his interest - in this case, the Dakotas. Sure, it'll cost us a fair bit to fly him there, particularly this year, but that expense also means the girls and I get to continue exploring rather than spend time RACING along our intended route JUST TO GET IT DONE! Even at 60+ days, I feel like we'll be moving along, but we don't want to be gone from home (read: Daddy) any longer than two months. Plus, there's a daughter's birthday to consider, and I think she'd like to be home for it, so that's our deadline for the return home.
I know that there are many other families who travel full time, taking their jobs on the road. This might work for you if you or your husband have a job that can travel (computer programing, locksmithing, RV repair, mechanics...). I like this idea, but my DH does not have such a job, and I haven't focused on my writing enough these mothering years to make it support our travels and daily needs at home as well (house payment, insurance, etc.).
If you have any additional questions, fire away!