I did a production of Titanic this past spring, though our stage is a fairly standard procenium arch set up, the only semi-odd thing being that the auditorium itself is stadium seating, so the first row is flush with the stage as opposed to the stage being raised above the audience. The biggest challenge we had was a ridiculous lack of wing/fly space, by which I mean, we had no fly space at all, and very limited wing space.
The set was modelled heavily off the original Broadway - basically a two-story, forty-foot structur meant to represent both the deck of the ship and certain rooms in the interior (in our case we had the 1st class smoking room and the marconi room under the main deck). It had seven front panels that could be removed/replaced depending on whether we needed one of the rooms below to be open. That was the main body of the set and it remained onstage the entire show; the mid-stage blacks were pulled across any time we were anywhere else 'in' the ship. Everything else - the two dining saloons, the bridge, the crows next and the "corridor" that's used in "Wake Up, Wake Up", were seperate set pieces that could be wheeled on and off as needed.
Unfortunately, we weren't able to tilt the ship for the sinking, though this was our original intention (the technical guy we hired to do this completely screwed us on this point).
Here are a couple pictures if you're curious:
So, this is the main set piece in fully closed position (this is the closing, full cast. As you can see there are quite a lot of us, so this was an issue too, space-wise)
Here is the set up for the "No Moon" sequence. It's hard to see, but the panels are off of the smoke room, since it's used later in the scene. The Bridge is on the left as you look, the crow's nest on the right. All of these rolled on and off.
Smoke room, with the panels off. Space and lighting were something we had to work out once we got in the theatre, but it was an reletively easy adjustment.
Aaand the radio room lastly. Again, space was an adjustment, but we allowed the actors (especially during the blame) to step out of the room so they weren't so squished.
Hope that helps or is at least somewhat interesting!