We do not use most of those amenities either on our cruises however it's nice to know that they're there for you. Oh, we'll duck into to theatre to see a pianist if that's one of the acts. We avoid the "Vegas" type shows. But you may want to give one a gander. Who knows? You might like it.
Your first choice is do you want to do a round trip or a one-way? Round trips go from either Seattle or Vancouver. One-ways go from Seward (or another that escapes me) to Vancouver or the reverse. We've only done round trips so can't comment too much on the one way trips however if you want to do and have the time for a land package to Denali, etc it must be one way. And pick a ship that visits College Fjord since you'll be in the neighborhood.
Seattle round trips I feel are more convenient. We fly in from SoCal. The negative about Seattle is the ship goes on the outside of Vancouver Island and there's much less inside passage cruising. That said, the scenery is still beautiful. It was much easier going in and out of SeaTac.
Vancouver round trips do sail much more of the inside passage. And on our 2 voyages they took different routes. The scenery is spectacular and it's fun winding around the many islands and passages. My negative is that although Vancouver is a beautiful city, it was a real pain to leave with huge lines at the airport for customs etc. Both times it was a weekend and maybe there are less crowds on the weekdays. 4 ships arrivived in the morning and all dropped passengers at the airport at the same time.
IMHO...a balcony is a must. You'll get many conflicting opinions on that. It is a lot cheaper to get an inside cabin. We are quiet too and really love the serenity on the balcony. We did however do a lot of walking around the ship as well. On Alaskan cruises there aren't any pool games and reggae bands outside so it's much quieter than say a Carribbean cruise. You will be able to find quiet spots on the ship inside and out and on the day(s) you cruise to a glacier you'll want to go up top when the side of the ship your cabin is on is facing the opposite direction. The Captain will rotate the ship. We will probably never cruise without a balcony.
I also feel that Glacier Bay is a must. Especially for a first Alaskan cruise. It's spectacular and while Hubbard Glacier is terrific, Glacier bay is better. This will narrow down your choice of cruise lines and dates however. Not all ships visit Glacier Bay and some lines (Celebrity for example) don't visit the bay at all.
One nice thing about NCL by the way is the Freestyle cruising. No set dining times and we found it easy, if we didn't go too late, to get a table for 3 (our son went with us) or in your case 2. It sounds as if you're not the type to socialize a lot you might want to avoid the tables for 8 no matter what line or dining option you choose.
If you like lounging around a pool and reading/relaxing, you may want to get a ship that has a covered pool. They close it up when the weather's too cold or if it's raining. HAL's are covered (and fresh water). Celebrity Mercury had a smaller covered pool and all pools were salt water. The NCL ship we sailed (now in Hawaii) wasn't covered and had salt water. All were heated.
There is a ton to do in all the ports. Some very expensive such as Flight seeing or landing on a glacier.
You can also however do your own walking tours. Many sites are right at the docks and so is the shopping. For 10 dollars (US) round trip you can take a bus to the Mendehall glacier in Juneau. There's a small charge for the visitor center at the glacier and hiking trails as well. Also in Juneau, if you're not afraid of heights, is the Mt. Roberts tram. It's right at the dock and there's hiking up top plus a shop and visitor's center. Whale watching with Orca Enterprises (Capt. Larry) was fabulous...not cheap however.
Ketchikan is small. It's an easy walk to cover the town and go to Creek Street, up the funicular, down the married man's trail, watch the salmon ladder, lumberjack show. The Duck tour was a kick and there are tours to the totem parks.
Skagway. We loved the White Pass rail trip. The line has spurs that pretty much back the trains to the ships. Town is a short walk away, depending on the docks and again all the shopping is right there.
We were delayed arriving in Sitka so didn't get to see much other than some shopping. The Raptor center is supposed to be really nice and I was sorry we missed it.
If you have any questions feel free to Email directly. As I mentioned, you'll get many different opinions on these message boards but that makes the search fun too I think.
