Something I would love to see added to structures is the ability to "lock" the placement mesh to a specific piece (the one you're looking at), then cycle through the snap points using the existing cycle snaps button. This would make it so that you can move around freely without the placement mesh jumping around while you check to see if it's going where you want. The only way to move it to the next snap point would be by pressing the cycle snaps button already in use while the left and right clicks place or cancel, like normal (moving out of range cancels automatically).