To each their own, but I'm definitely in the camp of not bothering with the pistol or spray. You and your buddy each bring an adequate rifle and you'll be fine. No need to buy the .300WM, your 30.06 is that adequate rifle.
While I certainly don't have the experience as some that have commented on here, I've been to the Rock a few times. And while I will echo what several guys have said in that you should be fine as far as aggressive bear encounters, you do want to be prepared if things do go left.
One night I did have a major pucker moment in the middle of a narrow creek with a pretty big bear. It was a "we surprised each other" kinda situation. No shots were fired, but it was REAL close to happening. Finger was on the trigger and it was itchy. HA! He kept getting closer and wouldn't back off. He eventually did and got out of there. He wasn't necessarily being "aggressive", but it was probably more about trying to figure out what the hell I was. It was real dark out and it took him a while to wind me. Had buddies that were deer hunting that had to give a charging sow a hair cut with a warning shot over the head at about 10-12'. Luckily the shot made her veer off, and she took her cubs and got out of there. No human or bear harmed.
Hell, you may never even see a bear, or you could see several a day. All that being said, keep your rifle near, be aware of your surroundings, and go out there and have a blast! Kodiak is one of the coolest places on the planet, IMO.