Bill,
This is/was the internal discussion I keep having. I went with the 15" MBP i7 Core machine with the high res matte screen. I love it. Takes some getting used to the smaller type on the higher res screen, but worth it. There are things I do wish for....more FW800 ports, but not happening regardless of which laptop you get. Then there is the EC/34 slot. I really wish that was on the 15" MBP like before. I would prefer using a card for eSATA connection to a drive or maybe even a RAID configuration just for faster transfers and video work.
Were I to do things again, I think I would still go for the 15" MBP like I have, as for portability, it is best. I do like the larger real estate screen and extra ports on the 17: MBP model however, but it is too big to carry about comfortably for my needs. I am thinking about the 27" iMac for the desk machine at this point, and just using the MBP for my portable needs. For now, I just connect my 15" to a 24" monitor on the desk whenever there, and that seems to work out quite well....until I have to struggle again when away from the bigger view ;-) No perfect solution. I would probably hook up the extra monitor if I had the 17" MBP anyway....cannot have too much screen.
LJ