One possible science niggle you may want to work out, which for all I know you may already have done: How is a Saturn-size Class M planet possible? To be Class M/Earthlike, i.e. a rocky world like ours, its density will obviously be much, much greater than that of a gas giant, so at the same diameter of Saturn its mass and gravity will be tremendously greater than Saturn's already humungous gravity (and non-humungous mass).
There are some rules about what would be considered human habitable. Above a certain gravity, the strain on the human system would be unhealthy. Comparing this to obese people on Earth isn't an apt comparison because it's not about weight but about gravity (a brain doesn't become twice as heavy due to obesity, for example). And weighing twice as much as you should isn't the same as the increased acceleration of higher gravity, which means impacts are more severe, etc.
Below .68G's planets will have a tendency to outgas their atmopsheres, thus rendering them uninhabitable.
Here's some basics, from another thread.
TGT pointed out to me that Stephen Dole's "Planets for Man" (aka "Habitable Planets for Man") is available as a free download from Rand.org
. I first learned about the book because it is cited in the TNG Writer's Technical Guide. I used it in designing the solar system builder portion of the computer game Rules of Engagement back in 1991.
From page 105.
The book is out of date in some ways, particularly related to theories about planet arrangement around stars, but a lot of the underlying logic and research still stands especially concerning the human animal in different gravities, why planets have to have short day-night cycles, etc.