If it's something you'll need to do frequently, or just multiple times...automate.
If it's something you need to do once, it's probably safer and easier to just suffer through it.
When we switch business applications a few years ago, it was my lot in life to sort out the mess that was our data for export/import. We had a list of 5,000 clients that was in in much the same state as you describe. Some people used address field 1, some people used address field 2, some people abbreviated, some did not ... It was a complete GD train wreck.
But in retrospect, it wasn't that hard to sort out in Excel once I started playing with the sort order and using replace X in column only. Because if you sort by the column you're working on all of the errors of a given type tend to get grouped by the sorting process, so they're easier to address it one shot.
Just a thought.