The no kids is by far the most important factor. They rape income and make all trips cost more, which is hard with less income.
Dual professional income no kid couples are literally rolling in cash and, if they aren't, they are doing something terribly wrong.
Kids change the equation but they don't have to rape you. Say you have 2 kids. You would be making a mistake to take a trip to say Rome with them. It's hot, touristy, and kids don't make good travel companions seeing historical sights and standing in line.
Instead you would probably go to Hawaii, Thailand, India, and other places where you could hang out on the beach and let them play. Maybe take them to Costa Rica where it's like being in a giant zoo. When they get older you could tackle some of the harder destinations.
Ideally though if you want to travel you will have friends or family either at your destination or going with you. Say your family goes to South Africa with your brother's family. You can then leave the kids with an adult while the other 3 adults go out and do adult things. You then rotate. This works out even better with more than 2 couples or with the grandparents along for the ride.
Your cost of living makes a big difference though. If you have 2 kids and are paying $2500 a month for daycare it can really hurt your ability to save money. However once the funds are in place you can look at your expenses in a new light since you automatically have a savings of $2500 that you won't have to spend on daycare while gone.
What makes it much harder for us in America to justify going overseas though is our tiny vacations. I wouldn't go to Europe for 2 weeks. I can't justify the airfare for such a short time.