If it makes you feel any better (and it probably won't), NW is charging $238.50 all-in for round-trip CMH-PWM K fares (with good availability). You could book your flights multi-city as DTW-PWM-DTW-CMH and save yourself some green. But I wouldn't recommend doing this too frequently as NW just may cancel your FF account. Also, remember not to check any luggage on your return.