patkhoo, i did thing of that but then I had the thought that from whatever orbital vector the planets where on there would be a variation in travel time depending on what side of the solar system they are on.
Here's a science fiction description for you:
1. Travel between planets ("phase lanes") in Sins is actually based on a series of wormholes. Wormholes, once established, link two points in space/time, regardless of where they may move in space. (Ref: Contact, Carl Sagan). This explains why the phase lanes are fixed between specific planets despite planetary movement.
2. Travel time between planets are also more or less fixed because wormholes traverse space/time. This is not like travelling faster than c, which requires as much time to traverse as disctance to destination. No doubt, travel between points is not instantaneous since there is some distance inside a wormhole. If you think about the folding paper explanaton of how wormholes work, you still need to traverse the paper.. But regardless of where the two points on the paper are, the thickness of the paper is the same, so travel time is the same.
3. Wormholes can exist anywhere, regardless of the effects of gravity. This is different from accelerating to c, or black holes.
4. This is true also for the part about star-to-star jumps. EDIT: In fact, in Sagan's Contact, it seems to imply that the stronger the grav field, the easier it is to build wormholes etc. Most of the big(er) wormholes are in orbits of dual suns, and his Grand Central Station is at the center of the galaxy. Earth surface on the other hand, could only have a small one 
Which explains why to jump to a different solar system, the wormholes are located at the stars.
5. A PJI can be considered as a device that sends out conflicting signals thereby upseting the accurate plotting of where a wormhole is. So ships need more time (900% to find the wormhole, but can still jump away after they have cleared the cruft away..
the phase lanes, if the planetary scale was the focus, would also be constantly rotating in a sickening motion ! not good for those early AM sessions when you've been playing for 6 hours+ could make the sleep depravation quite interesting.
If you were inside/on a rotating object, you would not feel quesy. This is different from you spinning yourself around for two reasons. If your object is rotating with you, your body has fixed reference points (the floor, window, etc) to steady itself, and if you are rotating, your body's sense of balance is being thrown off (inner ear etc). To prove this, if a person spins himself/herself around at 1000 miles/hr, of course he/she will be sick (or blown up by g-forces), but millions of people do it every day by standing on the equater of the earth, which coincendentally spins at 1000 miles/hr Again, there is a fixed point of ref on the equater and the object moves with you. This is why artificial gravity via rotation works without making you sick
Anyway, it is all up to one's imagination.. But if anyone here is looking for a very realistic look at space battles fought using sub-light and close to c speeds, then I strongly recommend Walter Jon Williams' "Dread Empire's Fall" series - http://www.walterjonwilliams.net/02_05_praxis_excerpt.htm. Consideration for accelleration of ships and missles, g-forces and manouvers etc. Until we figure out FTL, I think real space battles will be like this..
EDIT: I disagree agree with Tkins about the sounds.. In this future age, computers (AIs) finally understand that to increase the human(s) adrenaline rush (during battle), you must re-create the entire environment - hence simulated explosion sounds and even smells of burnt titanium.. 
