Re: Need advice on new rig and build
16:9 have both standardized to HDTV resolution and also, as they are lower resolution than 16:10 (1920x1080 instead of 1920x1200), they can fit more in a panel.
As far as monitor size, it depends on your preferences and your desk space. All monitors will display their native resolution sharply, their pixels will just be bigger. I personally use a 32" HDTV as my monitor and love the size.
As far as running games @1080p for the next 2 years, it should not be much of a problem if you get a good card now. Most high end card run things up to 2500x1600 (look at recent reviews), so 1080p will be easy and keep some headroom.
As the universe is curved, there cannot be a straight answer...