Went back to Batman Arkham City yesterday and finished finding the catwoman trophies. Also found another Batman trophy as well. When I got those, hostage #5 appeared and I was able to finish that off. I still need to find more so that I can unlock The Joker so I can fight him to beat him for an achievement. I'll work on that next.
I did get the Harley Quinn DLC at some point when it went on sale so I played through the entire DLC but at the end I started working on the achievements to knock them out. I got all but 3 so I'm running back through the DLC again to finish them. I found all of Harley's balloons before I went to bed last night. So knocked out that achievement. The last 2 I have left are to attach the blast sphere to 4 different types of objects, including people. If I would have read up on that achievement before just running through I would have knocked out that achievement on my first run as I accomplished some task differently so it never counted for what I needed to do in certain spots. After that, I have to finish disarming the alarms in under 3 minutes. Gotta love time based achievement. 8(
So I'll try to finish that up tonight and finish the riddler off. Then I'll be able to start working on running back through the entire game again if I feel up for getting that achievement.