If you go to http://gc.kls2.com (link also available on www.freewebs.com/flyingisfun ) you can calculate distance between airports, and they will add up segments for the entire trip.
Just multiply total for your elite/FC bonus, and add in bonus yourself at the end. Beware: it does NOT calculate 500-mile minimums.
I don't think site will give you airports to fly to based on miles; just do approximations. Beside, it's more practical to look at fares and destinations than pure mileage.