Delta upgrade certificates are one of the best benefits of elite status offered by any major US airline. There are two varieties – regional upgrade certificates (RUCs) and global upgrade certificates (GUCs). These instruments allow fliers to skip to the front of the pecking order for upgrades when booking paid flights.
For travelers seeking to fly in a premium cabin, upgrade certificates can save an enormous number of miles relative to booking an award ticket. In addition, upgrade availability is often in greater supply than low-level award availability, meaning you have a better chance of being able to work your way into a premium cabin in the first place.