I'm planning on an upgrade in early fall and I'm totally up in the air as to what that will be right now.
I've got an OLD iMac that needs to be replaced (late 2006 2.1ghz Core2Duo) though with the addition of an SSD it still holds up surprisingly well for Photoshop/Illustrator and even some 3d work in Maya and Modo. Most of my 2d design and development work is done on my 13" Aluminum MacBook (just before it was rebadged as the 13" MBP).
My plan was to sell off the iMac cheaply and replace it with the updated 21.5" model but now that machine may or may not exist. I've tossed around getting the MBP with Retina and hooking up a display to it but the jury is still out as to what non-Retina apps will look like on the Retina display. It seems almost pointless to get the non-Retina MBP as it's obviously hardware on it's way out and the Retina is only a few hundred more so I'm left sort of twiddling my thumbs.
I'm honestly tempted to sell off everything, get an Air and hook a display up to it for the time being.
Fig, I am like you ... and thinking much the same, except substitute a re-conditioned for the Air ... and got a price for a Dell 27" monitor, that is an IPS monitor.
My 2006 I think 24" 2.16MHZ only has I think 2GB of RAM. Its drive is gone and I boot off a USB port, from a 2GB USB 3 drive. I have a Firewire Raid mirrored setup with an older OS on it, and my important files. I have other computers too, but that is the one I use at home, and for my photography. I want to get my videos in order too, something I've put off for many years.
I could get a macbook pro refurb with a screen as good as today's imacs, and with Adobe certification (not sure though if they screens are so well built) for the price of a refurb iMac. And there is utility in the Macbook too. I could then sell a macbook I use, and then the 24". Although I worry about selling the 24" without a good drive inside it. The old one does work, but its flakey, and I'd need to replace it in good conscience ... but the time of adding a drive, and cost of doing so concerns me.
Oh well ... if only Apple would talk to its customers, and let us know what the hell they are going to do. Its not as if this iMac sector is full of innovation. And its not as if there is a Power Computing at loggerheads with Apple in a performance race. And people are so frustrated, some consider leaving the Apple environment. And because its difficult - with files and software - to leave, that leaves a really bad taste. And that makes Apple customers tell others, to stick with Windoze.
All because Apple cannot communicate with its loyal customers. Apple has totally lost its customer focus. They seem dominated by some distant design gurus, instead of being focused in our stable market here - the desktop arena - where customers simply want to know what Apple are going to do, and when.
Its hardly rocket science to communicate with your customers about what you are going †o do for them. Instead, we get spin and silence, and schoolboy secrecy. Its totally unprofessional.