Depends on where you are going, which side has land views, and which side sunset may be on. In other words, on most cruises it probably doesn't matter. Besides, you can always walk to a nice view point to see any available view.
If you havve a balcony and want breakfast outside, It is nice to have the rising sun on your side. Seems like trade-offs to me.
As Chuck says, it probably doesn't matter much. If you look at a map of your itineary, you can probably figure out which side of the ship will be in sun or shade at what time of day. It's impossible to guess which side will be facing port or sea when you're at a pier.
May be a little late in posting, but for future reference...
If you don't know already, the Port side is the left side (if facing forward) and Starboard is the right side. If you are interested in how your view will be while in port, post what ports you are sailing to. For example, in Charlotte Amalie, St. Thomas all the ships faced the same way (unless you tender), I liked the view from the port side better. On any given day, if you don't see the sunrise, you may see the sunset. From your map you should be able to tell which one you'll have and be able to plan a meal on your balcony for one or the other.