Holland America for fewer kids but there are activities for kids.
Consider a sea and land. Daniela National Part that you get to by riding train with sight seeing doms on the second level. This would be a little sea and more land. Most of your nights are in motels. Land can include Canada.
If you want to see glaciers have to go to glacier bay.
Get printed brochures as the number of options is very large and easier to review on paper.
Interior rooms are ok as you should spend your time outside of the cabin. The rooms will be small if that matters.
You will have to fly to the port so consider having the cruise co transport you from the airport to the port. Just makes the trip easier.
Be sure to fly in the day before you leave.
Check the temps but you will probably be wearing shorts in the afternoon. Point is it might be warmer than you expect.
Safety should not be a problem.
You will stop in Canada so I assume you may (probably not) need a passport. Check this out.
When you book you can request a table for x number of guest for the evening meal. Be sure to check dress code for "Formal" night ( not too formal anymore) and no shorts for dinner.
Get cruise lines apps as this might help.
Kids can check into the cruise ships activities for the day so check this out and see if you want it. Probably a plus for everyone.
You can start looking on the internet sites for various cruises to get a feel for the daily tours in the various ports. Try and figure out what you might like
This site will help.
https://www.cruisecritic.com/ Be sure to read the boards. Subjects are by ports and ships so lots of detail info.
You can start the cruise from Seattle or Vancouver and fly home from Alaska. Probably best for a land tour.