Golds get some extra points for their spend, and a 2pm late check out where available. And although it might not feel like a room upgrade, you may be placed on a higher floor or not directly facing the dumpsters...

I was never given a suite as a gold. But as others have indicated, doors opened up noticeably more at platinum. Even then though, there appear to a lot of platinums around thanks to bonus night promotions and credit cards. So what you might receive in terms of a room upgrade may depend on the balance of room types a particular hotel has and who else may be staying there that night. Upgrades are usually also easier on shorter stays.