Sitka was the smallest town along the cruise route, in comparison to Juneau, Ketchikan, and Victoria. The small downtown area, where the main dining and shopping options are located, is about a twenty minute drive from where the boats dock. The town provides free shuttles to and from the downtown area, which is very helpful, but do not forget to catch the shuttle about a half an hour before your ship departs.
When our shuttle arrived in downtown we were greeted by adorable children running lemonade stands(which is so smart!). At one lemonade stand they were selling Salmon Berry juice and muffins, which is a local berry that grows in Sitka(and does not actually taste like salmon). If they sold Salmon Berry flavored items at Target I would definitely buy them.
The most popular restaurant, which had a pretty long line when I tried to just look at the menu, is the Westmark Lounge. Our shuttle driver also pointed out that the restaurant made an appearance in the film The Proposal, so maybe that adds to its popularity. If you do not like seafood, then I would suggest eating at The Pub which has a bar food type menu but plenty of non-seafood options. If you need to eat last minute, there is a crab shack(actually more like a tent), right next to the cruise ships that many travelers enjoyed.
Overall the restaurant and shopping options were limited, but I would suggest stopping by the Alaska Pure Sea Salt Co. This was a really cool shop which sells different flavors of salt for seasoning food, as well as body scrub, candles, chocolate, wooden kitchen supplies, and other items. If you are going to spend your money somewhere in Sitka I would suggest stopping here first.