Oracle Enterprise Edition, while it has some nice extra features over standard edition, they are not worth the 3-4 times the price of Standard Edition.
Oracle forces you to license Enterprise Edition once you have a certain number of users, or over 4 CPU sockets on the server.
Standard Edition is available for servers with 4 or fewer processor sockets, and "Standard Edition One" for up to two sockets, and is very cheap.
Anyway, one of the minuses though of going with the Standard Editions is the loss of Dataguard / Standby database.
While there are commercial solutions which provides the functionality for SE, I just saw an article on dbasupport.com which steps you through the requirements to write/script your own solution. Well worth a read: Manual Standby Database under Oracle Standard Edition
BTW - watch out for Oracle licensing if you are running Oracle on VMWare - licensing is based on the number of sockets on the PHYSICAL HOST, NOT the number of virtual CPUs of the virtual machine in which Oracle is running.