Sheffield is central as folks have said. I like it 'oop there.
Skegness?? Plenty to do there including buying knock-off goods from the nearby market.
Fenland - new chef does a mean Carvery by all accounts.
Tatenhill/Derby? just 'cause I've never been there.
Breighton? Lots of interesting stuff to see there.
Anywhere where Pilot/Flyer are dishing out free landings.