To answer the actual question - I'd like to think a bit of both.
Cater for the masses (of whom are in the place) so they don't lose interest, because without them such a big event simply wouldn't 'happen'......but make damn sure the event also supports the original ethos of the Scene by including D.J's that put something fresh into their sets - and that doesn't mean completely new discoveries......I keep saying this I know, but I'll say it again - These 'Returnees', have been 'returned' for ten years now and don't need patronising, they will welcome fresh stuff if it is done 'nicely'
A few years back I was asked to get involved in a very large oldies venue (The Pemberton Centre) and at first took quite a bit of flack for introducing unfamiliar tunes, I had a few complete dance floor clearers, and at one point I had half a dance floor - No, I mean 'literally' half a dance floor, it was the right hand half of the floor actually, honestly, you could have drawn a straight line down the middle! It just so happened that on that side, was where people that travelled congregated, whereas the other side consisted of mainly locals that didn't.
No problem with that, we decided just to put me on for 45 minutes each one around 9.00 - 9.30 ish, and after a few months the 10.00 / 10.30 spot worked a treat. People got to know it was 'Lenny doing his bit' time. I had lots of fun jibes thrown at me like....."Ok, Lenny's on - time for a Pizza".....Or...."Crikey the bars packed, Lenny must be on"..... etc. Anyway, we managed to get the point across that we were simply trying to share more tunes, and they respected that.....Where it all goes wrong is when the punters are not familiar with the tunes, and get the impression that nothings gonna change all night - They then lose interest, stop listening, and go home unhappy, on top of which, they go and tell others how sh*t the night is.....then you're onto a loser.
Whatever though - It's never easy, In fact, I'd say it's harder nowadays - Everyone's a f*ckin' expert
All the best,
Len