I have done the Vancouver - Fort Lauderdale repositioning cruise twice - eastbound on the Ryndam, westbound on the Veendam. It is a wonderful trip - take plenty of film!! If you stop in Cost Rica, splurge on a trip either to the cloud forest or to the jungle. If you stop in Guatemala, really splurge on the Tikal excursion - Tikal is magical.
I have sailed on the Westerdam three times, all to Alaska out of Vancouver, and most recently a year ago. She does not have all the amenities, nor is she stylistically as attractive, as the newer ships. She was, however, in fine shape. The decor has been described as "country club" - very comfortable, not glitzy, lots of dark wood. Overall, there's more than enough on board to find kindred spirits with whom to have a good time and fully enjoy yourself.