I really love using Seller Tools, not only for creating sales, but for the treasuries. I think those help my sales more than anything. I've been able to make one very easily and quickly. The best part is the notifications you send out after the treasury is made!
I love the ease of promoting items in my shop through social media. I love that I can set automated promos as well as manual, because I can promote new listings easily manually and promote my existing listings with the automated version.