August 18--the day Starwood Preferred Guest and Marriott Rewards are merging into one unified loyalty program--is Saturday. Below is a checklist of things to make sure you've done before then, as well as some things you should wait to do on merger day/as close to it as possible (whenever their award booking reservation system comes online).

Identify SPG and Marriott hotels you want to book, and check if they are going up in price with the merger book before August 18.