Each weekend when Leon Panetta flies roundtrip from Washington D.C. to Monterey, California it costs around $30,000--you're paying for it, and he's only reimbursing you for the price of a coach seat. Since July, he's been home 14 times reports The Washington Times' Susan Crabtree who also notes:

Mr. Panetta must reimburse the government for personal travel at the cost of an equivalent commercial coach ticket even though the actual cost of the travel is much higher -- $3,200 a flight hour, according to the Defense Department. Each round trip from Washington to California and back, in an Air Force equivalent of a Gulfstream jet, can add up to more than $30,000.

They add that It's government rules that require Panetta must take a military jet for security and logistical reasons (keeping in touch with senior officials).  But, assuming each trip costs a flat $30,000, that would mean that since July, taxpayers have already spent $420,000 on Leon Panetta's commute and gotten (based on a price search for a ticket to Monterey in December) $6,594 back in return. Back in September, the Los Angeles Times reported that it was the frequency of his trips weekend trips (leaving Friday and coming back Sunday nights) that caused the criticisms. But rest assured, “He works virtually nonstop wherever he is, including on the weekends, and believes that he does some of his best thinking when he’s away from Washington,” an official told the Washington Times. “That kind of recharge helps inform his thoughts on how to move."