We didn't do any official excursions for Alaska. For us, it wasn't worth the cost. Also our DS has special needs, and we don't know until its happening, how he will react to some things.
Each port day, we got up leisurely, went to breakfast later than others (ordered room service fruit and pastries to hold us over while getting ready) then got off the ship. We just walked the town, and if something looked interesting, we did it. In Skagway we went to a playground, and DH did some geocaching, and we went in some shops. In Juneau we walked the strip, and took the mt Roberts tram to the top and looked around (just bought tickets at the bottom and got on). In Ketchikan, we walked around, then found a free shuttle bus, and randomly rode it to a park district. We went to this beautiful park with a creek with jumping salmon, and watched them. We were almost alone there!
Each day we did this, then got back on the ship at lunch time eat our paid-for-lunch, let DS nap, and hang out on the ship the rest of the afternoon.
We loved it! We didn't spend a pile of money, we saw sights, and we relaxed!