CPB,
This is a problem that has plagued us for years. What used to work best was the AAA TripTik planner. Unfortunately, unless you are carrying internet (wire) as you go, there isn't much that works right.
The TripTik planned still works, but it now includes all the local event and as such is too cluttered to be really useful. It also does not have enough range. EI, unless it is set to maximum range and you are careful, it will not indicate the Gilmore Collection in Hickory Corners MI (betwixt Battle Creek and Kalamazoo) and about a 20 mile diversion from I-94 and should not be missed even if you are not a "Car Person".
What I want is a program that I can load a route in and ask it what is along the way. For example, the Henry Ford in Dearborn MI, Crystal Bridges in Bentonville AK and Museum of the Rockies in Bozeman MY, should each get a tick if your are within 100 miles. But then there are no shortage of museums and attractions that are not worth diverting for you best route to see. I only need to know about those enough to read the reviews.
Reminds me. I need to write another letter to AAA.
Matt