<grin> You're essentially describing my childhood.
3 kids was the max my mum chose to travel with alone; 1 in the backpack, and one for each hand. That said, she took the 3 of us all over SE Asia (we were stationed in Japan, and every chance she got she popped us onto a plane, train, or boat and took off with us. Hong Kong, Singapore, Guam, S.Korea, Phillipenes, Hawaii, Thailand... if there was a SpaceA flight, we were on it. We also went up the length and breadth of Japan... from the hotsprings in the snow of Izu Wakimatsu, or snowfields of Hokaido... to the southern islands, Kamakura with it's bells as big as houses rung with tree trunks to the bustle of Tokyo. When we lived in the Far East, my Dad was out to sea 6-9mo at a time, and we were off on our own adventures 3-6 mo out of every year. When we were stateside, we'd pile into the car and just drive. 1500 miles, 3000 miles, you name it.
LOVED IT. (Except for a 2 year period where I was just a git, because I didn't want to leave my best friend, and became a major pain in the neck -age 10 & 11)
((In fact, for my son's early years, I duplicated it. I've been more than a bit remorseful that the past 3 years have been pretty sedentary... In fact, I had to cancel a 8 week trip to Argentina this fall (Cost: 2k)... Israel & Egypt the year before that for 6 weeks (cost $5k), and the Balkans/Turkey the year before that for 8 weeks (cost 2.5k) as well as a few other short trips. It's especially irking because we've been homeschooling for all 3 of those years, so theoretically could have just up and left whenever, taking our books with us. Well. Needs must. This year it was medical expenses, last year it was a tax screwup, the year before... ah well. We'll get there.))
After 3 kids, my mum wouldn't travel on her own anymore, but waited for my dad to be able to come with us... or took us singly to different places. Trips with mum were *always* coveted, but family trips were the best. Airplanes and hotels and hostels were second homes. As a matter of fact: Home is where your pillow is in my book.
My mum's experience on 3+ kids is this: 2 kids is 5 times the work of 1, 3 kids is half the work of 1. 4 kids onward is easier and easier at HOME; but when traveling one keeps wandering off and giving her heart attacks.
I have FAR too many personal experiences as a child to share just off the top of my head. Languages, people, places, my family... I had an absolutely GOLDEN childhood. I never understood people who didn't like climbing into cars/ trains/ planes/ etc with their families (these also seemed to be people who never went anywhere). My fam was the BEST! That's who I wanted to spend time with. The affected disdain/ boredom/ etc was just baffling to me. I mean, I tried it on for size from time to time, but I always forgot about it once we were on the road.
One hint: When traveling with kids... whenever possible, stay somewhere with a pool.
Any specific Q's (from a kid's perspective / hearsay from my mum with traveling with 3), or just from my own travelling with 1 (but sounds like you've done that and been just fine:)... PM me.