I agree with Grant. If you're responsible only for given databases, you should have only dbo privs as a max. I would also strongly recommend that all code being promoted use ONLY the 2 part naming convention to prevent any confusion (and, it helps performance a bit, as well) especially if there's some other schema in play other than just dbo. It will also help with an object accidently being owned by a user.

The "SA" user should actually be disabled. If DBAs actually need "SA" privs to do their jobs, for reasons of traceability, it should be a part of their privs instead of having them login as "SA" or some other common login.

If you need the 3 or 4 part naming convention because some object is in another database or even on another server /instance, DON'T use the 3 or 4 part naming convention even then. Instead, setup a synonym to do the job for you. If the name of a database changes or is moved to a different server, it's MUCH easier to redefine a handful of synonyms than it is to find all of the 3 and 4 part naming in code and changing it.