I've always done the Griswold family vacation. My dad, an amazingly competent person, always tried to control his vacations to the point that he knew what meals would have served each time we ate at a restaurant. After this, we always had to deal with the unexpected. This might be a 10 'extension cord when we turned out to need 12', or a car recall for possible shorts in the electric door locks we heard right after we stopped because the doors were on fire.
I've spent a few decades trying to foresee the next disaster and prevent it from happening. Perhaps, as a
reaction, I tend to be less structured in my vacations. I know where I'm going, and when I'll be there, but I tend to presume that I can deal with whatever comes up when the time comes. Thankfully, I've pretty much been able to manage without encountering major problems.
Either method can work for a good, enjoyable vacation. Knowing what kind of person you are, and what you want out of the vacation is required. Whichever plan you embrace, some preparation is required. You have to know what budget you can use. This is money and time at least. If you intend to fly, you will need to have tickets far enough ahead of time to get the best price. If you drive, the car needs to be serviced to limit the opportunities of something breaking at an inopportune time. A car should be stocked with an emergency kit, with first aid supplies, water, a blanket and possibly some survival rations of some sort. You should always keep an atlas and local map in the car.
Even when simply going somewhere reasonably close to your home town, you should always do your research. There are many little treasures you can find that are not normally considered tourist destinations. I've been able to visit places from movies, books and history that were not on any guided tour. Whenever possible, I ask people I know in person or through the internet about the places I intend to visit. This has worked both ways, with both the person living there and me, the visitor, likely to learn about the place.
One of the lessons I've learned from my father is that a spontaneous vacation, where you go to a city and then explore instead of following an itinerary, can benefit from planning. Like my father, I keep a folder with every document and message relating to the vacation. It greatly helps when the time comes to deal with troubles. The folder includes places that might be useful, like an embassy, tourist center, welcome center or other such site.
The most important thing to remember about a vacation is to enjoy it. Bring what you need for comfort, plan for multiple things you might want to do, so you have available options in case something does not work. Do not be afraid to follow your nose if you find something exciting. Just do not break the budget you set when you started.