(10) Peaceful solution: Leaving the main are of the hotel Deus Ex: HR Guide
Last update: 11 May 2016
Map legend: 1 - Main staircase; 2 - Fire escape staircase; 3 - Entrance to the ventilation shaft on level three.
If you don't mind stunning enemy units, then you can start doing that as soon as you've regained full control over the main character. There are about 4-5 Belltower guards on each floor. Try performing surprise attacks #1 to avoid detection and use your radar or your augmentations #2 to locate enemy forces before making each move.
If you plan on avoiding enemy units entirely, then you will have to use camouflage often (Cloaking System augmentation) and pay even more attention to guards' movements. Either way make sure not to be seen by the heavily armed soldiers stationed on the main floor of the hotel (screen above).
Your main objective should be to reach the bottom level of the hotel, because this will allow you to leave this area. I would recommend choosing the staircases #1 only if Jensen is capable of using camouflage. The reason for that is because getting to the bottom level #2 would require you to sneak past heavily armed guards and trying to eliminate them one by one would be extremely difficult.
Using a ventilation shaft is a better plan if you don't want to by seen nor heard by the guards. Start off by descending to level three. Proceed to the eastern group of pods and look around to find a vent cover #1. Get inside the shaft and walk through it to find an exit #2. Notice that you'll drop outside the main area of the hotel, so you won't have to worry about the soldiers with heavy rifles.
Important! The walkthrough is continued in Step 11 (Travelling through the locker room area).