You may want to open a local bank account for paying expenses in Euro: rental guarantee, monthly rent, utilities.
Recent employees have opened bank accounts with:
Through the International Treasury Services (ITS), you can set up a pay allotment for direct deposit into your local Euro bank account. Currency conversion is made at the US Treasury Wholesale rate. Information can be found in this folder.
There is also an Andrews Federal Credit Union on the installations in Brussels and Chievres. Accounts there are in dollars, but they also provide currency exchange and bill pay services in dollars and euros.