Three earth radii is a bit much even for my planet- I was thinking more like a radius and a half. This planet also has two moons; I don't know whether they're Moon-sized, though. I am thinking that they would be in some sort of orbital resonance with each other, and be used in early date-keeping. (For example, let's suppose the inner moon has a period of 15 days, and the outer moon one of 25 days, in a 3:5 resonance. Then several cultures would have a seventy-five day "month" based on the transit of the moons.)
A planet with a radius three times that of Earth is an interesting idea, because, I think, wide-ranging planetary colonization would have to wait for the steamship. But I'm not sure whether I want to do that.