I would love an Egret 2. Everyone seems to want one at the moment and so are holding there prices very well.
At the moment I have three Net Citys. One has a Sega 29e31s 31k, one has a Nanao MS2932 31k monitor and my main one I am working on I bought a brand new Sanwa PFX tri-sync for.
IIRC the original NNCs had toshiba tri-syncs but you never see them over here. All the ones that pop up either have the Sega 29e31s or Nanao MS2932 31k monitor.
There is no rotate mech on the Net Citys but they are not that hard to rotate unless you are a 7 stone weakling

I will be rotating mine all the time, it only takes a few minutes.
In regards to what type of monitor you want you should think about what type of games you want to play. I want to play 15k Jamma PCBS, 31k Naomi games, 31k Dreamcast and Xbox 360 and also 15-31k Mame games so thats why I went for a tri-sync.
There are other tri-sync cabs about like the Blast City that seem to be fairly plentiful, I think Jeff @ Digitalsystemdesigns imported a load.
If you want more Candy info you may want to head over to arcadeotaku.com, thats where all the cabs came from that were at R3play.