15 years has passed - it's time for a new mattress

Any buying tips? Does it need to be any more complicated than lying on a few at the showroom? Of course I know mattresses aren't lifetime purchases; my main concern is avoiding paying good money for something I'll hate in a few years.

I'm prepared to spend up to US$1500. I want a spring coil mattress. I don't want memory foam. Please lend me your shopping experiences!