The recommended octane rating for your Chevrolet Suburban depends on the model year and engine. The owner's manual is the definitive source for this information. It will specify whether your Suburban requires regular (87 octane), mid-grade (89 octane), or premium (91 or 93 octane) fuel.
Do not rely on generic advice. Using the wrong octane can lead to reduced performance, engine damage, or even voiding your warranty. Consult your owner's manual!