I agree with the other posters altho I don't know how a BMW rides. There are a few other things you need to consider.
How much do you drive per year? If you're going to do a lot of weekend trips, long ones, the coupe may not be the ride for you. As you say, comfort is important and with the G, you have to take into account that it's geared more toward suspension performance than cushy ride.
Also, you say within the next 4 years you'll go to another car. During those 4 years, can you guess-timate what KIND of driving you'll be doing? If it's highway rush hour and you're in a real city with real stop and go for more than a half hour, you'll want to think about/be more inclined toward an automatic vs. a manual trans.
If you really put on a lot of miles and expect to ride the car hard, meaning really getting on it and street racing to some degree, or going to some form of track racing like SCCA Solo 2, while the automatic is great, the manual trans may/will give you more control. Also, if you go over the warranty miles AND IF the auto trans breaks, it could be a very large expense to repair. I'm talking thousands not hundreds of dollars.
It's a trade-off: with the G35 Coupe in auto or manual, you get a car that performs very well with some compromises made to driver comfort. With most other cars, you get driver comfort with some compromises to varying degrees made toward performance. Unless you have two cars, it's very rare to have it both ways.
So, take the others' advice to heart and test out a manual in say a Corolla (definitely one of the easiest to learn/shift), and just remember the G35 Coupe or Sedan manual is a little more difficult and a little more work (heavier clutch feel which will add up if you're in 5 mph traffic for an hour, twice a day). And test out the ride of either Coupe or Sedan over rough pavement and on the highway.
Thanks all you G fans!
