Let me preface my argument for paper over plastic by letting you all know that Robin and I recycle both paper and plastic. Our paper is done at the curb and our plastic is taken to Safeway.
If you do not recycle, I suggest you ask for paper. There are arguments on both side, and if you have time, please check out this information piece: Battle of the Bags: Paper vs. Plastic- msnbc.com Very well done. My biggest complaint against plastic is the 100,000 animals that die each year from plastic litter. And, did you know that 14 plastic bags contain enough petroleum to drive a car a mile? Can't we come up with technology to convert the bags back into usable energy? Also, the non biodegradable factor is a huge consideration. I realize it takes more energy to make paper, but I believe we can do better. One thing that could be done more environmentally conscience, is using only recycled paper and Hardwood pulp from regenerating Eucalyptus tree farms. This idea was brought up by Simpson years back when they had the Shasta Pulp mill in Anderson. They bought land around Red Bluff off of I5 to do just that. You can harvest the tree and the stump will just grow a new tree. The trees are still just sitting there to this day. Other states also need to mandate pollution control standards, like the ones we see in California. If Evergreen Pulp can make environmentally safe pulp without the use of dioxins, others should too. (Evergreen is the only pulp mill in North America without dioxins. European pulp mills in Scandinavian countries are also "Chlorine free.")
Just for the record, Robin and I do have reusable carry bags that I always seem to forget when I go to the store. Reusable Bags :: Reusable Grocery Bags. This, of course, is the best way to help the environment.