For the map I'm working on, I want a BTS scene where a room with turrets lowers, and the player must figure out how to get rid of the turrets. I want the player to go around the room and find a button that will ram another room into the turret room, disposing of the turrets and letting the player go through. However, I'm having difficulty with figuring how to do this. My best guess is to have both rooms be prop_physics and have the second room be parented to a func_train. There are a couple of issues with this. First, I'm guessing that parenting will make the room surround the func_train. Second, I can just envision the player finding a bean can and throwing it at the turret room, making it fall. Finally, the ramming sequence will be rigid, and will not look natural. Is there a way to make free-spinning joints? Or should I make this a logic_choreographed_scene?

You also use func_door

A logic_choreographed_scene has almost no relevance to what you're trying to do. It would either be an animated model or a bunch of constraints with func_boxes and a func_door for parenting.

OK. Also, I have no experience modelling. I have Autodesk Inventor and SolidWorks (I'm a student, I get pretty much everything for free) but those don't seem like very good options for modelling for the Source Engine. What would be a better choice?

I use 3ds max. Try out the rayfire plugin if you want some nice destruction.