The summer is a great time to plan a family vacation. It is even better if you can incorporate your gospel teaching into this time that you spend together as a family. You can plan a long road trip and hit most of the church historical sites or you can plan a shorter vacation and only see one or two of the sites.
In the New York area you can attend the Hill Cumorah Pageant and visit the Sacred Grove and other museums that the church has set up in the area. This is all near around and Palmyra, New York. Additionally you can take the time to drive to Niagara Falls and see other sites. You can also include the sites at Kirtland, Ohio on your tour.
You may want to travel to Nauvoo, Illinois for the pageant there and also take in the sites on at Independence Missouri and Winter Quarters. If you are coming out from Utah you can also hit many of the church sites along the trail and in the Western part of the United States. If you enjoy the pageant you may consider volunteering to be in it one year. This is great way to spend time together as a family.
If you are not from Utah, you may consider planning a vacation to Utah and taking in the church sites there. There are many sites in Salt Lake City, but you may want to expand your trip to include the entire state. If you live in Utah, you may choose to visit one of these sites each month or for a family home evening lesson. It is important to teach your family about the heritage that the gospel has and to learn from the experience of the early pioneers.
Finally you may consider a going on an LDS cruise. These cruises go to many different locations but offer firesides, speakers and LDS centered activities in addition to the cruise. If you have teenagers you may consider sending them to EFY or another church sponsored camp to give them something to break up the monotony of the summer.