Sold! That's gonna be our plan. With likely walking tours/hiking in Ketchikan and the whale watching/glacier with marv in Junea. Does that sound like a nice balance? Lots of time seeing the scenery and simply being outside...Frankly, you aren't going until next year. I wouldn't be so fixed on selecting tours now. Your kids are in a very rapid state of change. A LOT can be found out in a year.
You have "selected" the most "popular" tours. There are hundreds more. Many find flightseeing a must- there really isn't any better way to see the vastness and beauty of Alaska.
But some facts- AVIS In Skagway doesn't open until 8am, but there will already be a line. You need to allow 5 hours for the drive. "Murrays" guide is excellent and "necessary" in my opinion.