I'd also love to know peoples opinions on this. I would say I am generally targeting search terms in this range and above, but I am just using this as a guide, and then checking to see how stiff the serp competition is, and i place more importance on that for sure.
I get this, but at some point the ROI time-wise gets pretty low for some low-search terms, even when it's really easy to rank. time is also an investment!
check SEO indicators like backlink number and RELEVANCY to see how easy it would be to compete in serps for keywords. I've seen terms with 80k+ searches/mo, with weak competition. I'd say that's definitely on the high end im-H-o, but I'm not expert at SEO so I'm sure others would be able to compete better (and have a different definition of "weak competition.")
hurr-durr.
Obviously you're already past this. I've been using SEO Quake toolbar (which is free) and finding it extremely helpful in quickly gauging serp competiton. I'd suggest adjusting the prefs to show PR, yahoo LD, and SEMrush traffic, and take out most of the other inline values for searches otherwise it gets super boated and yahoo will bitch. you'll see what i mean if you install it.
hope that helps.
-ss