How much do I tip for Alaska private tours?

[criscoloo]

14 of us going on a 3 hour Harv and Marv private boat tour in Juneau and a 7-hour private bus tour in Skagway. How much gratuity should we anticipate giving?

 

[DISNEY FANTASY]

We did six private tours in the three ports, I tipped 10% or a round amount depending on the service, our pilots of planes and helicopters had the highest for wonderful times.

On a boat if shared it's less if it's private then up to % but a round $ note for a family is good.

Before I went I read trip advisor on it and based it on that.

Personal to you higher, and if with others lower.