Do people actually still travel and attend certain venues because certain DJs are on? If so, find out who they are and book them.
I'd go for DJs than can play a mixture of eras and styles for hour spots. Plus maybe some that are more specific in their plays, but only let them have two 30 minute spots (stop the moaners kicking off?)
All the DJs should be there for the duration to stop repeat plays - they go on in ascending order of their alcohol tolerance.
Have a request sheet on the door for the DJs to peruse before they go on and hopefully oblige in their spot. Also, might stop DJs playing some cack that just want to hear and getting away with it by saying 'request' before they play it.