I used one of the sleeping suites today for my overnight layover flying TXL-IST-JFK. While I initially planned to go to the business lounge, M&S was just closer and I was lazy to walk. As far as I remember, the suites had their own private bathroom but these bathrooms were not allocated to the suites when I visited. Instead, the staff were using the showers for all lounge visitors and there was a 1.5 hour wait for the showers at 1 am. As I was going to sleep, I booked my shower for the time I was gonna wake up, and there were no hiccups when I woke up.
I’ve also had a chance to talk to a lounge personnel when I was waiting some drugs to be delivered from the pharmacy (apparently the landside pharmacy delivers drugs to the lounge, which was great for me as I didn’t need to leave the airside area). The personnel said that the M&S lounge is usually more crowded because guests are allowed. He also added that the only exception to this is the time when there are 4 flights to United States at similar times. At 5.30 am in the morning, the M&S lounge was indeed packed with people waiting in line for some food booths.
Regarding the exclusive lounge, he has not seen “any” work being done there and he does not foresee the lounge to be open soon.