That's a pretty big assumption, but I'll give my $.02 anyway.

First, I would expect that the DBA monitors the performance daily so that no unexpected problems come up. In addition, he/she should verify that the backups from the previous night have completed successfully. I would bet about 1 hr/day for both.

Next, I would have the DBA start looking at performance of the application. There are always ways to apply technology to existing performance problems (sometimes for the better, sometimes not). His/her expertise in SQL and PL/SQL will come in handy when optimizing the existing code.

Next, I would share with the DBA the expansion plans of the business. The DBA can look at scalability issues as well as participate in the DR plans.

The DBA should also be investigating the new features of 9i and figuring out how to exploit them for his/her business.

All this, of course, depends on what role the Management sees for the DBA. Some managers see DBAs as nothing more than programmers that know something about Oracle. Some see DBAs as Sysadmins with Oracle knowlege. I would fathom to guess each group has their own definition of what a DBA is.