Lots of good and not so good advice/information.
The good.
If you want to avoid children, go when school is in session.
Do fly in a day early.
Do buy travel insurance. Not from the cruise line but from independent insurers. ( TripInsuranceStore.com )
Visit cruisecritic.com for lots of good insights.
We went on Holland which has few children.
If price isn’t a big issue, look at the Haven on Norwegian, maybe $4500 per person.
Most cruise lines include alcohol in their basic price.
Most include one or two specialy meals in their basic price.
Almost all cruise lines do not all smoking in cabins or on balconies.
Very few cruise lines have formal nights were you have to wear coat and tie.
Don’t overpack. You’ll need half the clothes you think you will and twice the money.
Not so good.
There are multiple train excursions from Scagway. Not all require a passport, only those entering Canada.
Late arriving shore excursions. The cruise lines do not guarantee they will wait for you. Usually they will but not always. They do guarnatee they will get you to the next port if they depart without you.
The shore excursions are not operated by the cruise lines. Therefore there will usually be a mix with some booking direct (cheaper) and some not. Therefore it really doesn’t matter if you book direct or through the line, the ship will normally wait.
Other.
If you have time to shop around some travel agents will discount the cruise fare by around 8-10%. You do not have to book through the cruise line.
You can do some fake bookings where you visit the cruise line websites and pretend to be booking. You can step through the process up to the point of actually buying. This allows you to compare prices and benefits.
Do spend some time on cruise critic.
“Do spend some time on cruise critic.” (CruiseCritic.com)
But don’t even allude to anything political on the site. They have serious butt hurt about that - LOL!
I’ve been a member for at least 15 years and it’s priceless (free too!) for all kinds of info. If you don’t see answers you’re looking for, ask and you’ll get responses.