Hi! I just went on an Alaska cruise for the 2nd time last year in late June/early July with my family on the Celebrity Solstice out of Seattle (convenient for us because we already live here). We stopped in Ketchikan, Juneau, Skagway and Victoria. Fantastic views and awesome scenery. Our ship even had what they called 'the lawn club' where half the top most deck was a nice grassy area to lay out on. It only really got used much on the way back down to Victoria, but it was really nice for that day. That being said bring some indoor entertainment for yourself (books, DVDs to watch on your laptop, knitting, etc) so you don't end up just eating or drinking out of boredom all day on the two at sea days. You probably know internet onboard is super pricey and super slow too.
One warning I do have...being so early in the Alaska cruise season it will be COLD. You may not get to sit or hang outside much. Pack a good wind and water proof jacket and lots of layers to wear for when you're in port. You will likely get rained on during one if not all your Alaskan port days. We went just before the 4th of July and it was still cold. I went with my grandmothers on the same cruise on Norwegian in 2004 in August and it was warmer but still cold enough to need a good winter jacket at times.
Definitely go see the Mendenhall glacier in Juneau, take the train in Skagway (get some great views of the mountains and a feel for what the gold rushers went through when they arrived in Alaska to get to the Yukon). We had fun getting to meet some of the sled dogs in Skagway last year too. The Totem park in Ketchikan is a little underwhelming and I'm not sure it's worth the cost of paying the cruise line for a tour, but the lumber jack show was fun. Mostly it's fun just to walk around the town a little and check out Creek Street area and Miss Dolly's (Ketchikan's former red light district). Whale watching might be fun too, but May could be too early for them to have come back from Hawaii yet. I'm not sure if you're taking off from Vancouver or Seattle, but if you're going to stop in Victoria and never been Butchart Gardens is definitely a beautiful spot to check out and May will be great for seeing all the flowers in bloom. Walk along the inner harbor there as well, there's some nice harbor side bars that are fun to just relax at for a minute and take in the view.
Oh yeah, and don't be too disappointed if they can't make it through the Tracey Arm Fjord and have to turn around due too much ice activity. Still beautiful to look at the first part of the fjord even if you can't make it all the way through.
Feel free to PM me if you have any questions or want some other suggestions.
One warning I do have...being so early in the Alaska cruise season it will be COLD. You may not get to sit or hang outside much. Pack a good wind and water proof jacket and lots of layers to wear for when you're in port. You will likely get rained on during one if not all your Alaskan port days. We went just before the 4th of July and it was still cold. I went with my grandmothers on the same cruise on Norwegian in 2004 in August and it was warmer but still cold enough to need a good winter jacket at times.
Definitely go see the Mendenhall glacier in Juneau, take the train in Skagway (get some great views of the mountains and a feel for what the gold rushers went through when they arrived in Alaska to get to the Yukon). We had fun getting to meet some of the sled dogs in Skagway last year too. The Totem park in Ketchikan is a little underwhelming and I'm not sure it's worth the cost of paying the cruise line for a tour, but the lumber jack show was fun. Mostly it's fun just to walk around the town a little and check out Creek Street area and Miss Dolly's (Ketchikan's former red light district). Whale watching might be fun too, but May could be too early for them to have come back from Hawaii yet. I'm not sure if you're taking off from Vancouver or Seattle, but if you're going to stop in Victoria and never been Butchart Gardens is definitely a beautiful spot to check out and May will be great for seeing all the flowers in bloom. Walk along the inner harbor there as well, there's some nice harbor side bars that are fun to just relax at for a minute and take in the view.
Oh yeah, and don't be too disappointed if they can't make it through the Tracey Arm Fjord and have to turn around due too much ice activity. Still beautiful to look at the first part of the fjord even if you can't make it all the way through.
Feel free to PM me if you have any questions or want some other suggestions.