DLs can be a lot of trouble to keep updated, especially since there's no way to know what contact is in which DL except by opening the DL. I recommend using them only for relatively small lists that rarely change.

Using categories to organize contacts opens the possibility of easily performing a mail merge to email, which will result in each person getting an individual message, thus more likely to get through their spam filter. Also, if you want to put someone into multiple category-lists, you make one change in one place, their contact record.

Select the Category in "By Category" view
Actions > New Message to Contact