I actually prefer the multiple star system idea, mostly because travel times in this type would vary soooo much depending on where the planet was at the time, whereas times seemed pretty regular... oh well, I'm not an expert.

Tensen01: Lots of people do prefer the star cluster model, and it's a perfectly valid one. I'm not going into all the pros and cons here. However, I do think that the cluster introduces its own problems when it comes to travel times. Travel times between planets and moons in any one star's life zone would be very short compared with the travel times between the stars themselves. Each star system would be a tiny little grouping of relatively close planets with lots of open space between them and the next star cluster.

The formula I found is that the next nearest star in a cluster must be five times or more the distance from a star to it's outer life zone in order for planets in the life zone to not be affected by the ajacent stars gravity. In short, if the extreme outer edge of your life zone is 1 AU from its star (star A), then star B must be at least 5 AUs from star A. And that's just the absolute minimum: realistically the second star might be much further away.

In other words, travel time in a cluster would not be regular. If you are travelling within a star's system, distances would range from a fraction of an AU (a planet to moon, or planet to a planet in an ajacent orbit that's nearby) up to around 2 AU or so maximum, depending on the size of the life zone. But travel to planets in ajacent systems would be much further - 3 AUs at the absolute minimum, 5-6 AUs more likely, and easily much further if the star is more than the minimum distance away.

Which is not a huge problem, but for me doesn't seem to fit with the travel times seen on the show.