We kept our old treadmill in the lower level of our home that is unfinished and used for storage. There were no windows, no sunlight and the walls weren't drywalled. So, we were running next to insulation. We were inhaling all that icky stuff, it was starting to stink down there and those long (and even short) runs felt even longer. The kids enjoyed coming downstairs with me to exercise, and we kept toys down there. However, it was a job just to get everyone situated down in the "dungeon" with snacks, drinks, toys, etc.
We purchased a new treadmill a few weeks ago from Sears. I will be posting a review on my new NordicTrack T5 zi Treadmill (HERE) really soon. It was a sensible purchase. Reasonable amount of bells and whistles. It rocks.
My dad suggested that we move the treadmill upstairs. We have four bedrooms, but three rooms were taken as bedrooms. The fourth was used as our home office and toy room. I decided to clear out some of the big toys and get rid of things they've grown out of. After that was done, I cleared out our home office. This mongo-desk takes up two walls in the room. We purged a ton and packed away items that we wanted to keep, but didn't necessarily need to access.
The result is a nice, multi-functional space: a home office, a toy room ... and a new home gym!!