My first cruise was in 2564 on the Wonder (9B) and on the Magic we were in 6007 (11B sideways). A few thoughts on both cabins:
2564 was very quiet for us, but a great central location. We did not hear any noise from above or from any machinery. I liked the window and the light, but we really did not use it that much. I found that when I was seating on the sofa or the bed, I would only see sky in the window, not the sea.
6007 felt quite spacious with the sideways layout. However, there were two issues. Due to the side wall of the cabin being towards the hallway, I felt that hallway noise was coming into our room much more than in the standard layout. This was most noticeable with the cruise director's announcements. For us that was not an issue as they only happened during times when we were not wanting to sleep. But for someone who likes to sleep in or to take naps, this could be an issue. We generally did not miss the natural light in our room, but we did often put on the channel on the TV with the view from the bridge to see how weather conditions were. What we did miss was a space to sit indoors with a view. That was due to the fact that this was a cruise to Norway with cold weather and sometimes we just wanted to sit and read and on deck was too cold and all other lounges inside were busy with activities. We did not want to sit in out dark cabin to read. On a warm weather cruise when I hang out in a deck chair on deck 4 all the time, this would not be an issue for me.
We love being forward as we are only two adults and on the classic ships the adult things are all forward (bars and pool). So, for us this is a very convenient location. I think for families it might be less so. But then the classic ships are smaller and the walk to other places is never really that far. But the midship location on deck 2 on our first cruise was most likely one of the most convenient places to be at on the ship. The atrium was just above us and when we wanted an elevator, they were never crowded when we got on on deck 2.
Personally, I prefer oceanview, but I can do inside. For me it would depend on the price difference between the two. If it is only $100 to $150 more per person per 7-night cruise, then for me it is worth it. Once we are looking at a bigger price difference, I would be tempted to save the money and spend it on other things...