As of the first of the year, LA and most surrounding cities enacted a plastic bag ban for major retailers. The ban will extend to smaller stores this summer. I am completely in favor of the ban. Too many bags just get tossed out immediately after a single use. However, stores now have to charge for paper bags too.
Ever since moving here we have used paper bags from the grocery store for our trash. On the rare occasion we shopped at Target or somewhere without paper bags, we used the plastic bags for trash as well. After buying handy reusable bags for shopping in preparation for the ban and subsequent paper fees, we realized we needed some receptacle for our trash, so we purchased plastic trash bags.
But wait, this doesn't make sense! So instead of throwing away 5 or so plastic bags a month (full of trash), now we will throw away 30 plastic bags a month and pay for the privilege of doing so (we have a cat so daily removal is a necessity whether the trash can is full or not). Granted I got the tiny 4 gallon bags and the trash can itself is only 2 gallons, but that is still a big increase in plastic going to the landfill. This article points out some good alternatives to lining the trash can with virgin plastic bags: http://myplasticfreelife.com/2010/02/collecting-garbage-without-plastic-trash-bags/. The embedded video is pretty funny too.
Back when we had a house, it was much easier. I just scooped the cat waste straight into the outside bin, composted most food waste, and we were only left with maybe 2 bags a trash a week (usually not even stuffed full). I'm sure I'll think of something better than buying trash bags for next month.
On a side note, when will people ever learn that you can't put your recycling in the bin in a plastic bag. Drives me up a tree! Your recycling should be dry, so there is no reason you need any sort of liner.