WEll,
you can create new roles and privs and throw all the users, superusers in the their respective groups(where their read,write, etc accesses can be defined) on the server.

On the client side i would do the client installation with user option(you get three choices when you start client installation, i think) and the rest leave it as it is.


keep it simple, let the server take care of their access grants..
it's not a silly query amit, every setup is pretty different. for ex, here we have users(and also on board our ships) who access the database thru a vb6 application , tailor made program where i adjust the user access for different groups with this applcation, but like i said if your (end) users do not have such facility then let oracle do it thru the security manager take care of this.