I find one of the toughest things for people is to make a family photo look interesting. When you go on vacation someplace nice you want to take a photo of yourself there to capture the moment. However, lining everyone up in a line is usually not that interesting looking. One of the easiest things you can do is to have people at different heights. Even with just a few people it adds more visual interest. Use something available like stairs at a famous building or rocks at the beach and have people interspersed at different levels so that you are filling the frame with interesting content or making it more interesting. With kids, another good thing is to provide snacks and drinks and time to run around. If kids are grumpy and don't want to take a picture then give them 10 minutes to goof off and/ or have a snack. It usually changes the mood right away. I almost always have snacks and waters on hand a family photo shoots just to make life easier for people. If you are planning a big trip, consider hiring a professional where you are going to take a photo while you are there. It makes a once in a lifetime trip even more memorable. Happy Shooting!