Hello barbosa, and welcome to cruise-chat;
the consensus around here is that Princess and Holland America do Alaska best. I would say Princess has the most to offer your two children.
My feeling is if you are going to all the trouble and expense to go to Alaska, make the most of it and see some of the interior.
Princess has cruisetours from 11 to 14 days that combine a 7 day Inside Passage cruise with a variety of land excursions. They have 5 ships in Alaska this summer. A reputable travel agent that specializes in cruises would be your best bet at this point. I would recomment their largest ships, Sapphire Princess or Diamond Princess because of the variety of activities for the children.
Half the fun of a cruise is the planning and the anticipation;
don't let it overwhelm you.
If we can answer any more specific questions please ask.
Have a great trip and stay in touch.