Kasar:
There is a lot to pack for Alaska, mainly because the clothes are bigger. My husband and I went the first week of July, and it was warm for Alaska, we were in T-shirts and jeans a couple of days, but the rest it was long sleeve shirts and pants.
As for warm clothes, we bought waterproof jackets that fold into themselves to store when you aren't wearing them, and then fleece zip up jackets that you can layer underneath. When you go to the glacier landings for viewing or dogsledding they give you big heavy boots to wear, so you don't have to pack those.
We didn't take our children with us, so it was just the two of us and we had two very large suitcases and two carryons. We used the space bags to cram it all in!!