"Sitka Convention and Visitors Bureau" delivers excellent information how to get there and what to do in Sitka.
In Sitka you find sights from times when Sitka was called "Paris of the North": St. Michael's Cathedral, Castle Hill Park, house of the russian bishop. You can also see the Tlingit Tribal Show.
I likes especially the Alaska Raptor Center: it's a hospital where they care for wounded birds. After recovery the birds are returned to the wild when possible. In Sitka it's also a good idea to take a sight seeing tour by boat - besides sea otters and lots of sea birds I saw rain bows.
I also recommend a visit at the Sheldon Jackson Museum and of the totem poles in "Sitka National Historical Park".