I'm considering the high end 21" and the low end 27". I'm typing this on my early 09' iMac 24" 2.66. I was waiting to get a Retina display, but the new form factor has me intrigued and ready to buy. I have 1st and 3rd Gen iPads, 2 iPhone 5's, Roku, PS3, Xbox, and 3 Apple TV's on the network. Not sure this matters? The iMac serves as my main computer, about 6 months ago it started slowing up, slowing up a WHOLE lot... I keep iTune's, Twitter, Mail, iPhoto, Safari (usually, there are about 5-7 tabs open), etc. etc. open AT ALL TIMES. I do some minor CS4 work (family usually asks me to take photo's with my DSLR when we have an event and send them to them. I shoot RAW, touch up and send to them). I know it comes down to budget, but do you really think that the extra 5.5" and a different graphic card justifies the extra 300 dollars? Especially, since the last I heard you could stream your desktop through your Apple TV and this Mac will be in a room that has a 60" HDTV?