Select or exclude individual contacts/lists when sending email

Hey there! It would be great to have an efficient way to create exclusion lists. The tag system is a cumbersome process to go through when the goal is to simply send an email to List A, but exclude anyone who is also on List B. If a checkbox-to-exclude feature became a reality, you'd have a lot of happy customers! (I did search the "Constant Contact Community" when trying to find out how to exclude a list BTW.) 

I didn't necessarily want to post this particular message to the entire "community" but I couldn't find a way to just email my exclusion list request to your developers.

Thanks,

Kim