I think the following units of time should be totally and completely eliminated:
-Hours
-Minutes
-Weeks
-Months
And 1 second of time should be a different amount of time. Currently, there are 86400 seconds in a day. I think a second should be slightly shorter in length so there are 100,000 seconds in a day. The unit of time are:
1 day = 10 decidays
1 deciday =10centidays
1 centiday = 10 milliday
1 milliday = 10 decaseconds
1 decasecond = 10 metric seconds
Then units of time will be much easier to convert. This is after America goes completely metric in all other regards in 2 years.