Remember that you might not be able to travel with kids in the same way that you used to travel without them - to a degree! Kids can be more flexible than we think if we lead by example. Don't assume you won't be able to visit museums or try interesting new foods.
That being said, it always helps to find activities that specifically cater to children. We've found that a mix of activities geared towards kids and adults keeps everyone happy.
Build in rest time. It might seem like "wasted" time when you want to see as much as possible, but an hour of rest can save many hours of meltdowns later on down the line.
Screen and snack limits do not exist when trying to keep kids occupied during a long flight.
Buy your kiddo(s) an inexpensive point-and-shoot camera. It keeps them engaged and gives them ownership of their experiences, and it's so fun to look at the images later and see what caught their eye compared to yours. Expect lots of photos of cats, especially if you travel to Montenegro!
And finally, the number one tip is.... go and do it! Many parents and caregivers feel so anxious about the idea of traveling with kids that they just don't. Is it going to be a perfect trip? Probably not - but it just might be.
Great notes - I love the camera idea!