Whenever I see a new opportunity to earn bonus miles, I try to assess the amount of time (and hassle) involved vs the number of miles or points I will get in return.

At one extreme are the credit card offers, where one can get 25-30K just for filling out an online application form. At the other, one can get 100 miles for stopping in a store or doing a test drive or some other time consuming activity.

Do you have a guideline as to how much time you are willing to invest for how many miles?