OK, so you'll have both the laptop and a desktop. That's good. Both sizes of the iMac will do everything you listed without breaking a sweat. So, I think physical size is the real issue for you. Will your intended desk space reasonably accommodate the 27" iMac? For instance, mine wouldn't because of the height of an overhanging built in cabinet shelf. Another thing to think about is viewing distance. Some people, like me, have difficulty shifting the eyes back and forth across really wide screens. We loose track of the lines of text and keep getting lost while trying to read from one line to the next. So, we like to keep our web pages smaller than the screen. Unless you're into displaying multiple pages, that means a really wide screen may be wasted on you. There is also the issue of vision to consider. The bigger the screen, the further back you will tend to sit. If you wear glasses, particularly bifocals or continuous lenses, you may find it annoying to have to hold your head in awkward positions in order to get proper focus toward the edges of a really large screen. I use the 23" Cinema Display and wound up buying an extra pair of glasses just for computer reading.
You are going to love your iMac regardless of which one you buy. Congratulations, and welcome to the forum.
