I've asked another question about trinary planet systems which turned out to not be possible.
Is there a way for three worlds to co exist within sight of each other? Sight being defined as making out continents with the naked eye.
The planets need to be large enough to have gravity of 0.8g, 1g and 2g (ish), humans can have minor modifications (thicker skin, stronger bones) to survive but are essentially the same as they are now.
I'm now thinking of moons orbiting a gas giant, but I don't know if this would work with them having to be close enough to the star for heat & light and whether the gravitational stresses of the planet would make life too unpleasant.