We likewise feel that there was a calculation of whether the kids would get anything out of the cost and effort for young kids. When they were very young we tended to only choose things that maximized our time and attention on each other.
In the first two years or so, it was mostly stay-cations. Taking a week off to build a fort in the back yard, or a slip-n-slide, putting up a tent in the yard and sleeping outside, then taking a bike ride on some trail and picnicking. Local hikes, nature centers - the kind of thing that can be done in one day.
When the kids were about 2-8 we took a lot of supported overnight rail-trail bike trips. Sleeping in a tent for several days, biking all day, stories, singing. They had little books in the trailer. The longest trip was 8 days, riding from DC to Pittsburgh. There would be occasional weekend excurions to include a beach, the butterfly conservatory in Ontario, Climb Mount Monadnock in NH (a 4-mile hike but lots of elevation), lots of campfires and campground exploration. We hit some historical sites, Concord Bridge, Baltimore shipyards and the like. We had to just plan that their attention span was less than ours and we would not get to read all the plaques. Making them go our pace spoiled the fun for everyone, so we decided to instill a love of travel rather than instill our needs. There were also trips to visit relatives, so again more kid/family-centric.
After 8 was when we started doing cross-country road trips. I did them as a kid and remembered the destinations fondly and don’t remember being too bored, even the trip in the station wagon from Boston to Guadelajara, MEX. So we started taking ours out. It was always tent camping, always by car (minivan) and usually more than 4 weeks. We picked up camp nearly every other night and went someplace new. We had them do the “Junior Ranger” programs at National Parks, which allowed us to linger over the signs more.
I just asked my daughter, now 18yo, what she thought of the long drives, and she says she doesn’t remember being bored. She liked to read and look out the window (start them as babies having soft “books” in the car! Being able to read in the car is a treasure.) We had a joke that a parent would shout out, “Beautiful View Alert!” And the kids would look up from their books and say in unison, “oooooh! Aaaaaahhh!” And go back to reading. We also had a rule, “No Books in National Parks, look out the window”; because they would just keep reading.) She also remembers how we stopped at rest areas regularly and always (it was “required”) had running races for the full length of it several laps before getting back in the car. She said that was key in breaking up the day when we had a “long drive” like the sprint from Pennsylvania to Missouri when the goal of the trip was the pacific coast, or the northern prairie stretch from Montana to Minnesota. She also said having a vehicle where you can easily and broadly see out the window is extremely key. She got bored in the station wagon when we took it to visit relatives because the seats were too low to see out. Get a minivan.
We went on a month-long mega-trip 5 times, eventually hitting 47 states, 5 Provinces and 2 Mexican states and climbing 25 (so far) state high-points. And the kids say they have fond memories and want to do more. We’d try to stretch their capabilities with longer and longer hikes, so by the time of the first cross-country trip (ages 8 and 10) they were ready for a 9-miler in Glacier National Park. We did have actiities in the car, for example every time we crossed a state line, one of the kids had to read the size, population, state bird and flower, etc. from the atlas, and the other read the entry from “How the States Got Their Shapes”, and the license plate game and playing alphabet with signs, and roadside bingo.
We started doing “City” vacations only when they were in their teens. And my youngest was 14 or so before we took the first airplane vacation and they were taken to LegoLand and DisneyLand, and she was 17 before we got to Hawaii.
So, summing up: We made the trips very kid centric early on to not waste time or money on something they couldn’t appreciate and would cause frustration because we wanted to appreciate it. I have no regrets of that - we ended up with kids who love travel, new experiences, who can appreciate slow quiet moments, stare long at the world around them and really SEE what is new and not already known to them.