I understand what you mean by covering a broad spectrum of subjects. I guess at this point, it is hard for me to critique a reel that is 3:30 long, so some of the best advice I can give is to say you should cut it down a bit. Perhaps not 60%, maybe down to 2 minutes or so. If you are going to have a reel that is 3 minutes long or so, you need to tell a story with it. Perhaps incorporate a couple songs that will then portray certain emotions for these different subjects. That way, as a viewer is watching your reel, they feel more involved and there is something else keeping them interested then just relying on your shots. Showcase your editing as well you know?
All I am trying to say is, over 3 minutes is a long reel. very few large productions I know have a reel that is over 3 minutes long. the last thing you want to happen to somebody (perhaps a future client) is to get bored or uninterested while watching your reel, so keep them involved in the edit.
an example of a 3 minute reel that tells a story-