Don't forget about Enschede (near the German border)... You can visit Deventer during the day (it is a nice small town) and then head on to Enschede to enjoy the nightlife there. Enschede is also a student town so heaps to do there. Enjoy the fun and have a Grolsch beer in the town where it's brewed.
A one-way train ticket from Deventer to Enschede will cost you about €10 and the trip will take 45 minutes. A return is €17.80. There are also discount options available. Just check the Dutch train company NS for prices and schedules.