The wire is the way to go, it's really all you need. However here in washington we have some exceptional slugs and I'd like to share a little about what ive seen. the first thing was this mob of slugs attcked a 3 foot tall plant. So many of them got on the plant that it actually fell over, they then proceeded to slime the plant to the ground so that they had shade to hide in under the plant so the didn't have to leave in the heat of the day, I wish I had pic's but that's no bullshit. I saw it with my own eyes.
That's when someone told me about the wire. I tried it and actually watched a slug crawl up to it and start to climb the stem as soon as the touched the wire it recoiled in horror and left after thoroughly inspecting it for weaknesses.
Now the crazy part is one slug actually figured out that if it climbed a nearby grass stem and got to the correct side of the stem he could pole vault onto the plant avoiding the wire all together. A little brush trimming solved that problem. Slugs love the weed and will go through remarkable efforts to get some and they are smarter than you might think. They are really slow and have 4 eyeballs they have to think about something now don't they?