We did the Voyager of the Seas in November (the last Italian route before it came to Galveston) and it was the best cruise we have been on. The ship and crew were fantastic and the excursions we booked from the ship could not have been any better. I would vote for Voyager of the Seas.
We have also done Alaska twice, and it was incredible both times. It all depends on your family. My girls were 17 when we went in November. There was a lot of walking on the excursions we did. We left the boat around 8:00 and didn't return to 8:00. We wanted to see and do everything we could. In Alaska it is a lot easier to get around. The ship docks right in town and you can just get off the ship and walk. It would be easier to go back to the ship to eat or rest in Alaska. Which ever you decide will be great. They are two different types of cruises. You won't be disappointed in either..
My wife and I were on Slendour in 07, we did the same cruise out of Venice, the ports were a little different; but we enjoyed it so much. The ship (splendour) was a little smaller but the ship was in great shape, the crew was wonderful, and the weather was outstanding. We went in May 07. I will be on voyager this May; also going to Europe so I can't tell you about her yet; other than she will be coming out of drydock on May 13th. If u have any questions regarding Splendour and cruising out of Venice, I have a members review posted from 07
Freedom of the Seas Dec 11
Allure of the Seas: Jan 11
Voyager of the Seas: May 09
Splendour of the Seas: May 07
Explorer of the Seas: Jan 04
Majesty of the Seas Jan 99