Please use timezone EXIF data when available.
My camera (Canon 5D MK III) records the timezone in the EXIF info. It would be very helpful if Lightroom would use that to correctly order images taken in different zones (IE convert to UTC then sort). Images with no timezone info could reasonably be defaulted to the local timezone. Or better yet the timezone field could be editable. And of course the TZ should be displayed in all date/time fields.