If you plan to get the euro circulation coins from just one country, Belgium may not be the best idea.

There are eight denominations, and the Belgian ones all have the same obverse (country specific side). Here is a "diversity ranking":
Austria, Greece, Italy, Slovenia: 8 different designs
Cyprus, Finland, France, Germany, Luxembourg, Malta, Portugal, Spain: 3
Netherlands: 2
Belgium, Ireland: 1
(Monaco, San Marino and Vatican issue few coins, primarily for collectors.)
Here are images of the common reverse designs:
http://www.ecb.europa.eu/bc/euro/co...ndex.en.htmlClick any of the "All Sides" links on the right to see the country specific sides.
Christian