First Class staterooms D-19 and D-23 on RMS Olympic. On the Titanic, these rooms would have been nearly identical.
For anybody who is accustomed to only seeing pictures and renditions of the most posh first class staterooms of Titanic, the more spartan look of these rooms, with their simpler furniture, decor, and bare riveted-steel ceilings with their exposed beams, ventilation ducts and pipes may come as quite a surprise. In reality, only some of the first class staterooms on Titanic were as luxuriously-appointed as, say, the staterooms shown in the film Titanic. The amidships B and C Deck first class staterooms were the best, being the ones that are usually shown. However, the first class staterooms on the Boat Deck, forward of the Grand staircase on A, B, C, and D Decks, and the alternate first/second class staterooms on E-Deck were much more plain.
Image source: TOCL