I made a couple of trips up to Sitka when I lived in Seattle. Fished with Denny Cook, it's been since the mid-90's that I went, so I don't know if Denny is still in business, but do a search on Denny Cook Sitka for contact info. He and his wife had a B&B and Denny ran his boat out of Sitka harbor.
From what I remember, the best King fishing was in June before the commercial season started, we always went in August - not many kings at that time, though I remember catching a couple - coho were running at that time, one day we got into a massive school of them and caught out limits of 6 per person as quick as we could drop the line under the boat - fish were all 10-12 lb, nice size for coho.
We also did some halibut fishing out of Sitka, it takes an hour or two to get out to the halibut grounds, it can be rough, so if you are prone to sea sickness, keep that in mind. Average halibut were in the 15-30 lb range and at that time it was a dalily limit of 2 per person. One of the guys with us caught one that went 135 lbs. Halibut fishing is a chore, fishing 300 feet deep with heavy weight, and if you get a good one it's a long, hard slog to get it to the boat. It's good to bring some halibut home, but if I was to do it again, I'd probably just stick to salmon.
Sitka is very scenic, good chances you'll see some whales.