I replaced my old 24″ Dell UltraSharp monitor with a new one recently, because the old one was suffering from ghosting and burn-in (note to self: They’re called screensavers for a reason. They can save your screen. Use them.). I thought seriously about upgrading to a 27″ or a 30″, but from a cost-benefit and pixel-density perspective, the larger size just isn’t worth it.
As shown above, the 27″ gives you 60% more screen area (in pixels), but it costs 83% more (for consistency, I’m using current, non-sale prices). And the 30″ gives you 78% more screen area (in pixels), but it costs 150% more.
And then there’s the issue of pixel density (PPI, pixels per inch). The larger screens have higher pixel densities, so everything (images, fonts, etc.) will be more tightly packed, and therefore look smaller on the larger screen (16% smaller on the 27″ and 7% smaller on the 30″).
I have pretty good eyesight, but as pixel densities rise and text and images start to compact, I start to have to strain to see them. I think I might be able to adjust to 101 ppi, but 109 ppi is just too compact for me.
So, for now, I’m sticking with my trusty 24″ @ 94ppi screen.
Note: All this pixel-talk falls to pieces when discussing high-pixel-density displays (like Apple’s Retina Display) which utilize density-independent pixels (a.k.a. virtual pixels).