I use a 15" Macbook Pro. I agree that more real estate is almost always a good thing, but I decided the weight and portability issues trumped the extra few inches from a 17". After six months or so, I feel I made the right choice. Every time I lug my computer from the car to a cafe, or carry it down the street in my bag, I’m glad I don’t have even more weight and bulk to manage.
I have a 23" Cinema display at home, which is where my graphics tablet also lives. When I want to use my computer for kicking around in the world of graphics (e.g., running Photoshop or Painter, or iPhoto, or assembling a talk in KeyNote) I use the big display. When I’m just knocking out text, the MacBook Pro’s built-in screen is enough for Scrivener and a couple of smaller windows. I often have a copy of the Firefox web browser running (for checking email and searching for reference materials) and iTunes (for listening to while working in a cafe).
A couple of extra inches of screen would be nice to have in the portable, but to me, they’re not worth the weight and bulk. I’ve been 100% happy with my 15" MacBook Pro for writing, and the bigger display and tablet for bigger tasks at home.
In contrast to some other people’s experiences, my MacBook Pro gets warm on the bottom, but the top (where I rest my palms) is always cool. Even the bottom never gets beyond warm. At this moment I’ve been running for a couple of hours (plugged in), and I just put my palm flat against the bottom plate near the power connector (the hottest part of the chassis) and it wasn’t even uncomfortable. This is normal for me - my computer has never gotten much hotter than “rather warm”.
A few other random Mac observations:
I carry my MacBook Pro in a soft sleeve from InCase. It’s nice and keeps it from getting scratched up, but it’s rather floppy. I carry the Mac (in its case) along with all my other stuff (notebooks, pens, headphones, power charger, etc.) in a Teager shoulder bag. Everything fits perfectly, and I trust the shoulder strap and other connectors completely.
When my MacBook came, I installed a MarWare wrist pad (it’s a thin soft strip that fits below the keyboard, with a cutout for the mousepad). It makes for a very comfortable place to rest my wrists, and helps prevent my accidentally triggering the mousepad with the balls of my hands. It does make the lid slightly harder to close, though.
Finally, when I got my Mac I saved the thin white plastic sheet that the factory put in between the keyboard and the screen. I’ve had laptops in the past that over time picked up screen damage from the keys when the unit is closed (both from mechanical rubbing against the keys, and from the oils from my fingertips transferring from key to screen). I figured if the sheet’s good enough for Apple, it’s good enough for me, and now every time I shut my MacBook I put that thin white sheet back in place over the keyboard. I don’t know for sure that it’s helping, but it doesn’t hurt.
-Andrew