You want Glacier Bay which you will sail for most of a day. This means Princess, HAL, NCL, Cunard, Viking, Seabourn (although these can change from year to year). Some smaller ships too, but with the kids I would recommend Princess. HAL and Cunard are great but they are likely to be more boring for the kids. Celebrity does not sail GB.

For Glacier Bay a ranger comes on board to speak and answer questions as you sail the bay..

I would definitely suggest Princess. They have a strong children's program, especially in the summer. They have been doing Alaska longer than anyone. Do not do a round trip out of Seattle as you will see less. Do a one way northbound or southbound. Get a balcony cabin on the land-facing side. Book soon as these sell out quickly.

Outdoor pools weather? It depends. You might have a glorious warm days or it might be cold and wet. It's Alaska in the summer.

As to months to go, June, July and August are all peak, with July being most peak. Least expensive are May and September.

If you book early you can find (or a TA can find for you) two connecting rooms. You will need to assign one adult to each, but you can get your medallions or keys assigned to open either door and no one cares where you actually sleep. Easily arranged if you book soon. Another option is a balcony cabin and an inside cabin directly across the hall. Your TA can see exactly what cabins are available and how the beds are configured.

With over 1300 sailings each summer, Alaska cruising can be quite confusing and complicated so you might want to consider working with a TA who specializes in Alaska cruises.

I can't emphasize enough how quickly these are filling. Make a decision soon. I am already seeing limited cabin availabilty on popular dates.

Also, with most of these if you book now with a refundable deposit, if a better sale comes along, you can usually get it re-priced, as long as you are before final payment date.