places that do not require driving. I love and have always loved traveling with our kids. We lived in Japan with the older kids and travelled all over Japan and to Hong Kong with them. In the US we have travelled all over the western US and to Florida with the kids. Loved it. I have discovered that with bigger groups though that my joy is increased with these things:

1. Travel somewhere or somehow that there is a car available for most every or every married couple. Sharing cars between families increases stress and reduces joy.
a. If you are somewhere that does not require a car ignore 1. such as an all-inclusive resort with good excursions, cruising, somewhere with great public transit or somewhere like a Disney vacation where you are going somewhere that doesn't require a car every day.
2. If I am traveling somewhere that I feel that having everyone traveling / doing things together is important, small groups are important. We took the kids (3 married couples and the youngest single) to Hawaii. Broke rule #1 and coordinating times just added stress, reduced joy. Plus, a couple of the group need alone time. It was a good trip, but could have been better.
3. I really love traveling with just my spouse or the 2 of us plus 1 kid (and spouse, if married). We took all our kids when about 12 on a vacation of their choice. Left the siblings home with relatives. Wonderful vacations. A year to 2 years ago we took each kid (and spouse for the married 3, oldest with grandkids) on a vacation somewhere drivable. It was wonderful.

My wife's family has vacationed together a few times, but not recently. It was stressful. Coordinating with the group (what the group wanted) reduced the joy, increased the stress.

My family (parents, 7 kids and families) take a vacation together yearly. Some years 2 vacations, but not often recently as the number of grandkids, especially older grandkids has grown. As long as it is to somewhere that everyone can drive to it is generally very enjoyable. We try to spend time together for a meal most days and at least every other day spend a part of the day together in some activity. The group does things by family separate or with a couple families the other days, depending on preferences. The expectation that only about half the days have coordinated activities reduces stress and increases joy and fun.

I have enjoyed trips to Mexico and Fiji (visiting my parents on a mission) with all my siblings and spouses. Again about half the days we planned to be together. Half doing whatever. Most days we ate at least 1 meal together. These were fabulous vacations. Both were places where cars were not needed.

As others have said, long travel by plane with young kids is significantly improved when you plan to make the trip (in plane / vehicle) better. Plan for food, treats, activities... that the kids will really enjoy, especially things that might not be readily available to them when at home that are calming (no activities that will hype them up and not sugar / caffeine). We took the kids trans-Pacific 8 times (4 round trips) while the oldest was 4-5 and the middle 2 were 1-2 (twins). Generally able to make that a decent experience.

For long road trips movies that are familiar with good dialog (so the driver can enjoy somewhat) or audio books are great. Anything with Jim Dale as the voice (Harry Potter and many others) is a great choice for audio books. Jim Dale is amazing. We also passed around the device choosing the music we listened to for several hours where the only requirement was that they choose something no one hated and that was fun to sing along for a road trip. That was really fun.