I think that is a perfect way to celebrate your 50th birthday! Your husband sounds very supportive too! Map out your route and figure out where you can stay along the route...that will help you break down your mileage per day. There may be some segments where you will have short rides and other days that require more mileage. Planning the trip is half the fun and gets you motivated to train. Take pictures and please let us know how it goes. Have fun!