I need about 1 1/2 cups of flour for making cookies but would like to include some whole-wheat flour in the mix. In what proportions should I mix regular all-purpose with whole wheat for the best results?
Part of the answer depends on what kind of cookies you are planning to bake. The change will be more noticeable, both in appearance and taste, if the cookies are either thinner or whiter, such as sugar or gingerbread cookies, and less obtrusive in more robust ones like oatmeal or chocolate chip.
Whole-wheat flour is coarser and more gritty. It also has a somewhat tannic taste, which some palates may construe as bitterness. The cookies are thus likely to be denser and darker.
To find out your tolerance level, it is best to do some experiments. I'd start by replacing about 25 percent of the all-purpose for delicate cookies. For more sturdy ones, you can start off with an even 50-50 mix. The new white whole-wheat flour will let you start with a much higher ratio with almost no taste or textural differences.