We will have sailed 34 days on the Wonder by the end of this year. Last year we did 21 days on the Magic and 7 on the Fantasy. The underlying footprint of the Magic and Wonder are nearly identical. An outlook area was added to the Wonder for Alaskan cruising, but that is mostly, if not entirely, dedicated to concierge guests at this point. The programmatic differences are in dining rooms (Rapunzel's vs Tiana's Place), and then shows (Tangled vs Frozen). Tiana's Place is one of the best dining room experiences in the fleet, at least IMHO.
The crew on the Wonder is very experienced, across the board. I would have no concern about dining room servers - we have had some of the best on the Wonder. We have done 23 Disney Cruises and the Wonder is one of the best crews. It is a "secret" amongst crew that once you get a contract on the Wonder, you really don't want to leave. The Wonder does some great itineraries, and that is part of the reason crew love the Wonder.
Personally, we prefer the classic ships to the newer ships. Part of it is these ships allow for just a little better chance to get to know your crew because they are just smaller ships compared to Dream and Fantasy. They also don't feel as crowded. And, finally, the itineraries are just much more interesting. As you continue in your
DCL journey, itinerary may become more important to you and the Classic ships have Alaska, Canada, Pacific Coast, and Europe in their itineraries, along with Panama Canal and Transatlantic.