First thing I would do is create an impulse response. That way you'll always have access to that location through Altiverb, TLSpace, etc. (Or at least a pretty close facsimile to that space).
After that, it's anything goes. Drop some metal, squeak some hinges, pop some balloons, scream your lungs out.
Check out the last question / soundcloud file here. That should give you some inspiration.
Just had a thought as I was drifting off to sleep. How can you take advantage of the height of the space? Not sure if you can get up to the top, or how good a result you'd even get, but what about unfurling a really long piece of fabric, shaking waves into it, ...
Planning. Draw your design get the measurement. price of wood adds up fast, especially when you buy extra. it shouldnt cost more then about 300-400 for the wood for an 8foot by 2 foot pit. not including the tiles, terrain, and whatever else you want to put in the pit. also a good idea to make it in sections when you can lift a door to get to a tile, ...
Play with what Richard King did - play with an outboard LFO hooked up to a PA system (e.g. your Genelecs) and record it interacting with the space (in Richard King's case it was a sound stage on the Warners lot). That's how they created some of that money LFE goodness for Inception.