Suggestions for visitation schedule after I move two hours away from my children's father?

I am moving after the first of the year about two hours away from where I currently live. Right now, I am the custodial parent but my ex husband and I have our three children (ages 9, 5 and 4) equal amounts of time. Currently, we live about 25 miles apart. He only sees the kids on his days outlined in our Divorce Decree. He takes no part in any extra curricular activities for our kids, such as Cubscouts and therefore, my son has had to forego being in Cubscouts this year. I have no family in this area, and his family has literally stated that they in no fact are willing to help me. When my kids are sick, or are out of school, I have nobody here to help me and have to miss work in order to stay with them. Therefore, I will be relocating to the town where my family lives about 2 hours away. I want nothing more than for my kids to maintain a relationship with their dad and will do everything in my power to ensure that they see him as often as possible. I'd even be willing to drive them to see him every weekend if that's what it took, as well as any school breaks, holidays, etc., then we would exercise joint custody during the summer months. If anybody has any suggestions as to possible visitation arrangements, it would be appreciated.