I think you would be best having multiple planets that are gravitationally locked with one another as in a planet/moon system. A prime example would be Pluto and its moons (largest Charon). Charon is so large when compared to Pluto that Pluto doesn't completely command it gravitationally...Charon actually drags Pluto around as well. The result is that the two (as well as the other moons) all revolve around a void space between them whose location within the system is based upon the relative masses of the bodies. The spot that is the center of the system would be closest to Pluto since it is the largest of the system and commands the greatest amount of gravitational pull. The net effect is that the Plutonian system orbits the sun and Pluto seems to wobble (as it is orbiting the Plutonian System's center of gravity). Eclipses of the sun and each other would be common as the bodies would be very close to one another. The effect of seeing "moons" that were of this type would make them appear in the sky several times the size of the host star. Nights would be twilit often times due to reflected light of the other planets. One thing to consider would be how close would be considered too close...if they were too close together, their gravity might cause collisions or they might tear each other apart (that might reduce the size in the sky and amount of reflected sunlight). Lots to research and consider before attempting...tides would also be wild...

As to the prescience of life, if they were in the habitable zone and all had the requisite elements/conditions, it would be more alarming if only one had life while the others didn't. There is a theory that basic life may have "seeded" Earth millions of years ago from elsewhere (Mars?!?) and that it was ejected into space through a collision which later fell onto Earth within space rocks. Some of the theory holds water when you add I. That meteorites on earth have been found to have Martian origin. So ultimately, microscopic life that develops one one would easily traverse and seed the others in a system. Keep in mind that such an event would be highly devastating to the planet of origin and life on it (the impact would have to be great enough to send rocks into space and would likely be considered an extinction event). Life on the planets would evolve separately (with the potntial for some microscopic aliens from time to time) and would result in different species on each planet. Also keep in mind that cosmic events would likely affect each planet unless one or two were shielded by the others.

I think you would be best having multiple planets that are gravitationally locked with one another as in a planet/moon system. A prime example would be Pluto and its moons (largest Charon). Charon is so large when compared to Pluto that Pluto doesn't completely command it gravitationally...Charon actually drags Pluto around as well. The result is that the two (as well as the other moons) all revolve around a void space between them whose location within the system is based upon the relative masses of the bodies. The spot that is the center of the system would be closest to Pluto since it is the largest of the system and commands the greatest amount of gravitational pull. The net effect is that the Plutonian system orbits the sun and Pluto seems to wobble (as it is orbiting the Plutonian System's center of gravity). Eclipses of the sun and each other would be common as the bodies would be very close to one another. The effect of seeing "moons" that were of this type would make them appear in the sky several times the size of the host star. Nights would be twilit often times due to reflected light of the other planets. One thing to consider would be how close would be considered too close...if they were too close together, their gravity might cause collisions or they might tear each other apart (that might reduce the size in the sky and amount of reflected sunlight). Lots to research and consider before attempting...tides would also be wild...

As to the prescience of life, if they were in the habitable zone and all had the requisite elements/conditions, it would be more alarming if only one had life while the others didn't. There is a theory that basic life may have "seeded" Earth millions of years ago from elsewhere (Mars?!?) and that it was ejected into space through a collision which later fell onto Earth within space rocks. Some of the theory holds water when you add I. That meteorites on earth have been found to have Martian origin. So ultimately, microscopic life that develops one one would easily traverse and seed the others in a system. Keep in mind that such an event would be highly devastating to the planet of origin and life on it (the impact would have to be great enough to send rocks into space and would likely be considered an extinction event). Life on the planets would evolve separately (with the potential for some microscopic aliens from time to time) and would result in different species on each planet. Also keep in mind that cosmic events would likely affect each planet unless one or two were shielded by the others.