[protomyth]

The last system I had to do that had to have good dates - I did the following:

Past events had the local time, UTC, and time zone entry stored. Storage isn't much of an issue and it helped to keep things straight. Future events were only stored in local (8pm Dec 12, 2012) with time zone. Calculations were done on UTC with future events computing UTC on the fly. Reporting and actual day something occurred was kind of important. A day skipped would be an issue.