I would suggest you to visit Lipno, which is a beautiful place to visit. it will take one whole day for decent coverage. if u would like to try some ferry u can stay out. other than the cities, I would suggest one place named Divici kamen. it is quite difficult to reach this place but if u are a nature lover, it is worth visiting. Experiences: in March u will have rafting in the vlatava river and camping in the forest is very common in Czech republic. and trust me that will make ur trip. U will also find various kinds of fishing, u can try witnessing that, the kids will have fun with fishing.