We use

• Perforce for version control
• PowerDesigner for table creation and maintenance. Both the PowerDesigner file and the generated SQL file (create statements) are checked in Perforce
• RedGate SQL Compare to detect the changes and then build a a script to update each database.

We can get 60-80% of the changes generated by SQL Compare. The rest is hand crafted as we  use the scripts in an upgrade of our product. The integration of the generated scripts with the manually written scripts is sequenced in a batch command file.

Hope this helps others who are thinking about version control and upgrades.