Thanks to all of you who responded. i will put the Dunes and Potato Creek parks on my to do list. I have visited several Indiana parks and I'll give you my impressions for what they're worth.
Brown County - Nice Vistas great woods I don't like crowds so you won't find me there on an October weekend
Chain of Lakes - I just visited this one this fall. Very peaceful, great lake canoeing. I've been to the Minnesota Boundary Waters, this had some of the same feeling for me and no portages.
Clifty Falls - A nice canyon, for me I'd say this is similiar to McCormic"s Creek in terms of the topography.
Pokagon - I just visited this one on the same trip as Chain of Lakes. Great lodge. The only place in Indiana I've seen float planes. There were three on the beach and several flying over. More of a developed feel than most of the parks, but the campground looked very nice. Much nicer in my opinion than Brown County or Turkey Run.
Shakamak - If you have kids who like to ride bikes and fish this one is worth a look. Very peaceful during the week.
Turkey Run - Ive beent here in February and on Labor Day. I'll choose February. Nice canyons in the sandstone.
For those folks looking to stretch a dollar the Indiana State Park Lodges offer a winter special. Stay two week nights for the price of one.
DNR - Division of State Parks & Reservoirs: State Park Inns Home
Uplander