We take a lot of road trips, and tent camping has definitely been the way to go for us. What I particularly like to do is plan trips where we camp the majority of the time, but break things up with occasional motels, visits with friends/family, or even week-long stays in airBnBs, which sounds like it might be a good option for you. Take my advice with a grain of salt, however, as there are rarely children involved!
Anyway, tent camping is cheap (at least once you have your gear & car), simple (as long as you don't bring too much stuff), and has a relatively small footprint. It is especially cheap in places with more public land (AKA the West, generally). As two people who camp a lot, it takes us less than 15 minutes to set up or take down our entire camping set-up...but again, we are not also tending a toddler! When we camp with our nephews, we do plan for trips where we spend several nights in each place, as it's just simpler than trying to herd kids every morning & evening.
I haven't spent any real time RVing, but from years of observation, RVs seem to come with various challenges. It can be hard to find parking in some national parks (and some campgrounds, actually), driving narrow roads is harder & riskier, they take a lot of gas and overall chores, and every RVer I've ever observed brings too much stuff. But I can see some advantages too, and I think you'll have fun with whatever you choose.
[edited since I just saw your most recent post]
Your current plan sounds pretty excellent to me. Glacier NP has a pretty narrow window when you can visit and see the whole park, which might limit that part of your trip, but it's a gorgeous place. If you have lots of time to prepare, then you can also take "practice" camping trips closer to home, to figure out what you like (and what you can/can't live without).
One thing to research is whether you need to reserve campsites in the national parks you want to visit. Many have 'first-come, first-served' campgrounds, but they can fill up remarkably quickly, so reservations can be a huge help. CA also has some great state parks and other areas worth visiting.
Have fun planning your trip!