We haven't been on either, but we've been on both of the sister ships, Zuiderdam and Noordam. These two ships are identical, and so I would presume the Westerdam and Oosterdam would be also. The ships are very easy to get around. They are larger than the older, smaller ships, but you don't seem to notice the extra length... or maybe we didn't notice it because it was so long between cruises . . . As with all HAL ships, the appointments are beautiful, the ship is spotless and there are fresh flowers everywhere. The crew and staff are always on top of everything and ready to help you with anything. The entertainment areas are in close proximity with the exeception of the Crow's Nest, which is, of course, up on Deck 11. The Queen's Lounge is next to the Disco which is next to the Casino, with the Sports Bar, Casino Bar and Piano Bar all adjacent. All of which lead to the Showroom. The Explorations Cafe - library, computers and coffee shop are well positioned and very welcoming - my husband can tell you how to nap in the oversized leather armchairs with matching ottomans. Didn't use the thermal spa or the other spa services or the gym. The Lido buffet was very good; the ice cream station is open from 10:00 am to 11:00 pm. We had concerns about the size when we first anticipated the Zuiderdam - 1900 passengers ? ? ? Didn't notice - there is space for everyone. The only issue I had was that I thought the inside cabin was small (was smaller that on the Ryndam and the Zaandam)- my husband thought it was just fine. Either ship is a good choice.