Add the ability to "travel via"
Add the ability when putting in a destination to add a road or route you want to travel by. If you are going to NYC as a destination Waze client gives you 3 choices, but if you have a specific road you want to travel by you should be able to put that in.
Scott M commented
Yes, this. I sometimes drive from south of Boston to mid-Rhode Island and I'd like to enter my destination like 123 Main St via 18, 106, 24, 495, 295, post rd and have it use those roads (including realizing that the best way from 495 to 295 is 95S.