Same Sheryl.
When an airline requires an overnight stay (or more often a Saturday night stay) in order to qualify for a discounted fare, a way to work around that is to buy two separate roundtrip tickets as follows:
Ticket 1:
1/1/00 IAH-EWR
1/8/00 EWR-IAH
Ticket 2:
1/2/00 EWR-IAH
1/9/00 IAH-IAH
This way you qualify for two fares in the $200-$300 range. Use only the outbound portion of each and throw away both returns. If you just need to go to New York one day and return the next, it'll cost you nearly $2,000. So ~$500 vs. $2,000. It's called back-to-back ticketing and it violates fare rules. In other words, you can't fly the trips out of order. If you're caught, your tickets are cancelled and you jeopardize your FF account (they reserve the right to cancel it).