First, the page size must be large enough for the largest row possible (consider max varchar sizes). You may need different page sizes for the database.
In general, in a pure OLTP environment with relatively small to medium size rows (normalized) that are almost always accessed via an index (unless the table is very small), the page size should be 4K.
If you have a pure Data Warehouse environment, and SQL statements do a lot of table scans to access the data, the page size should usually be 32K.
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390