I currently don't have a Mac. Thus, I don't know the answer for a Mac.
A few weeks ago, I upgraded my Win XP monitor from 19" to 24". Then, I went into Control Panel - Display - Advance and changed its 96 DPI to 126 DPI. Font size is now perfect - for my new 24" monitor. Can "font size" be increased on a Mac machine as well? If no native setting, does someone have a shareware tool - that will increase font size instead? Just wondering...
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It can be changed natively, but it is really for specific applications that the font size will actually change in. They talk about it in this thread.
@OP- I can understand your sentiments on the large screen, especially with how bright and vibrant the IPS display is. You'll probably get used to it, as my current setup is my 21.5" iMac with a 32" LCD right beside it for my PC, but occasionally I link the iMac to the 32" via HDMI for Photoshop projects in which I need a lot of space. The 32" was super overwhelming at first, but now I love it.