You can convert PDF's back to AutoCAD pretty easily and accurately. But this is still the best way if you sending drawings out of house. If you start looking at different formats then your clients have to have those readers to read them.
One thing I like to do if you must send a client a dwg file is to lock all the layers, and the use a layer filter to make them all dissappear. 90% of the people I deal with can't figure out how to unlock them because the don't know about the filters.
Also using paperspace/modelspace usually causes them some headaches and they usually give up.
If you talking in house, we had our IT department only give write access to our drafting group to our drawings folder, that way no drawings could magically get changed without coming to us first.
We also took away everybodies autocads, which really helped. We gave them a free viewer like edrawings, solved 99% of our problems.
Haven't tried this, but I would imagine that you could save a dwf file out everytime you hit the save button. Should be easy enough.
-cadnutcase.