How would you suggest reaching Spa (Belgium) from the Charleroi airport? I haven't found any shuttle option below 150 EUR, which is quite expensive. Is there a reasonably fast train connection?
I was focusing on Charleroi because flying there seems the cheapest/more comfortable option, but if you tell me that I'd be much better off from another airport I can reconsider. Spa seems to be almost equidistant from Brussels, Charleroi and Cologne. Liège and Maastricht are a bit closer but they are also much smaller airports, which means one more leg and more expensive flights.