Well, for me, I definitely assess on a case by case basis. I have to say I haven’t tried any IE max-width hacks ... I’ve got that to look forward to at some point in the future.
With so many old versions of browsers still in circulation and low screen resolutions being in the majority, a lot of the time fixed-width makes more sense than liquid designs. But, saying that, it depends on the design, required features etc. - and what mood I feel in at that particular moment in time
I don’t do a lot of client work as such so probably have more freedom in the choices made - when I’m doing a website as a favour for friends they’re generally happy to be getting a website at a low cost and let me have bit more of a free-rein on the design elements.
Even then, I make sure the site looks okay in the 800x600 to 1280x1024 range - definitely a case of applying the 80/20 rule and getting a best fit to the intended audience.