An 8 day week would be far more efficient than the current 7-day week we use, and add billions of dollars into economic circulation. This is not a new idea. The Romans used an 8 day week.
The new weekday may either be called "Newday" or "Funday," and should be added between Sunday and Monday.
The normal 12 month calendar would not change, because weeks do not sync with months the way things are right now anyway. The added day would give more time per week for entrepreneurs and small business owners to focus on side projects, heightening the likelihood for success, and adding to the economy through the addition of new ventures and added consumer-spending hours to the year.
This is a politically neutral proposal.