Repeat Guest Tag Automation

I would love a way for the Tag Automation feature to have a way to tag repeat guests. This should be simple to do by having a workflow to select bookings of 2 or more. I like to acknowledge repeat guests, offer promos, etc. so having this feature would be incredibly useful. 

I would also like this feature to include a way to automatically apply a discount to a booking if the "Repeat Guest" tag is on.