Hey! We don't have any specific guidelines but we typically base gifts on actual interactions we've had and milestones the client has achieved. For long-term clients we usually send something small for birthdays. Whether a client has mentioned a favorite high-end brand of coffee during a conversation or small gift cards to a restaurant/coffee shop they've mentioned.
Really depends on the client.
We've never been a fan of gifting branded merchandise or doing than you cards, etc that I see a lot of companies do.
This is for our digital marketing clients, as we have a pretty personal relationship with all of them. Our hosting clients don't get anything special other than a notification about new value-added features (at this point).