I have monthly folders and keep everything for a year. When I finish filing this month, I clean out last year's for the same month and shred everything. Anything tax-related you're supposed to keep for 7 years, I think, but so far I still have everything since I started paying my own taxes. Anything house or home-improvement related I tend to keep indefinitely, too.
Before we got a shredder, I had a bad habit of letting them pile up for a couple of years (in the monthly folders)... I'm trying to get better. Most of mine are paid online and I have 'budget' documents that usually keep the same info, but the bills still get mailed to me.
It isn't a bad thing to hold on to utility bills and have the chance to compare... could clue you in on a leak or some other problem. Same with CC bills... see how you're spending money better/worse/differently than a year ago. <shrug>