Princess Cruises do trips to Alaska you could get some more details from them about what they do.
Yes p&o do very good cruises and always have good lecturers on board
Yes - we would strongly recommend Princess cruises - we did the inside passage plus the pre tour of the rockies and enjoyed every minute.
Take a look at Voyages of Discovery for this kind of adventure/educational cruise.
My friend and I went on a Celebrity Cruise up the Alaskan Inside passage in May of this year. We flew to Vancouver and picked up the Celebrity Mercury ship. Absolutely fantastic! they had a man on board called Brent Nixon who had worked for the govt or something up in Alaska for 16 years. What he didn't know about Alaskan wildlife etc wasn't worth knowing. He did an hours lecture with slides, video etc in the ships theatre every day normally in the morning and he was brilliant. He could even mimic the wildlife noises. By far, he was the most knowledgeable and fascinating man I have met in a long time. Go on a Celebrity cruise, you won' regret it!
I've booked through North American Highways to travel with Cruise West. I don't go until next August, but it looks amazing. It isn't large ship cruising though, so it depends what you're looking for.
I sailed with Celebrity on the Mercury about 7 years ago and they brought on board Alaskan Rangers one gave talks and the other stood on the bridge pointing out species etc of interest as we passed.The other thing to look for when booking make sure that you are to visit Glacier Bay this is not always included but definitely a must se.
We did Princess and had a great time. Rangers were onboard for a whole day. All week we had a Canadian lady onboard who gave wonderful lectures everyda.
Ncl cruise the inside passage with aguest speaker coming board while visiting glacia bay returning via outside passage a wonderful experianc.