I can't help you with an individual NP but can comment on living in Alaska a bit, I lived there for 5 years.
Sitka is stunningly beautiful, all of Southeast Alaska is. The primary reason it's so beautiful is the precipitation. It rains quite a bit which creates the lush forests and awesome landscapes. Let me repeat, it rains a lot, like moss grows on anything left outside, including things like cars.
It's also isolated. Sitka is on an island and you cannot get there any other way than flying or by boat. There are some roads out of Sitka but they don't go all that far, and maybe only to one or two small villages. And that's a pretty big deal if you've never lived in a place that is literally cut off from other places. You can't just jump in the car and do a weekend road trip. You need to jump on a plane to go really anywhere and you're probably 2 or 3 flights to Seattle, and those flights aren't cheap.
All goods have to be shipped in by barge or plane, so things cost a bit more there too, groceries, etc. Things like fresh dairy and produce will likely cause some sticker shock.
In general, I think you need to be comfortable in a small, rural community. I have a good friend of mine who has lived there for many years now and she loves it. I would recommend visiting for a week or so before fully committing. good luck.