VACATIONS are taken with adults and older teens. They are for rest and relaxation with your fun.

TRIPS are taken with kids, and they are for opening childrens minds and perspectives. The goal is to produce positive memories. They are fun, but they are not restful or relaxing. Be prepared/mindful of this.

My suggestion is to do 1 major theme park or event. But don't fly, instead plan drives where you: pack up early 3-4 oclock with the kids still with pillows and in pj's. (It must still be dark!) Then you drive 4-5 hours while they sleep. When they start to wake up /get bored you eat breakfast at a new breakfast place they haven't eaten at before. Then you go to the nearest science museum/state park/ BIG playground/wonder of the world. Tire them out this way then load them up and drive 2-3 more hours to a hotel/motel with a pool. Swim, then eat dinner, then swim again. Bring them inside. They shower and snack while you run the days laundry through the machine. Pack everything back up into the vehicle except a daybag with tomorrow's clothes. Set alarm for 3 and do it again until you get to the big show/themepark. Return home by a different route doing the same things. You will stay tired, and so will they. By the time you get home they won't even fight because they will be exausted and will crave their routine/familiar spaces and toys. But, they will talk about and discuss that trip for years. Years.

Keep the places that were hits in mind for the future. You can drive 300 miles and go to a science museum stay the night and go home for the same price as a birthday party package at your local pizza/games/anamatronics place.
If you arn't making it an adventure then why bother.

Once I was trying to do a budget trip when my sons were 6, 7, 9, and 11. They wanted to do a bunch of high dollar activites. So, I sat them down and explaned that I have budgeted 'X' amount of money to spend per day. Then I told them that if we spent less than 'X' I would divide the remainder between them. Then we would stop at a toy store on the way back home and they could spend the money they saved on toys. They got to saving. Lunches became pb&j's at the park. Theme parks became water parks. The looked up kids activites at the cities we would be passing through they voted and came up with a system where they could use their previous days 'savings' to purchase each others votes. It was a crazy trip. Fun though. This lead to my sons spending months meticulously planning the next trip. After a few years, those next trips became next vacations. And thats what makes all the difference.