We stayed in a 1BR last year and had 2 kids on the pull-out couch, but DS is autistic so I have added safety concerns!
As mentioned above, feel free to bring childproofing gadgets from home, as well as nightlights and baby monitors.
The patio/balcony doors are "french door" style, not sliding doors, but they do lock. We attached a string of bells to the door handles in case he tried to open them, as an added precaution, we pulled in the 2 little resin chairs and table from the balcony each night so he would not have any way to climb up over the rail.