The king salmon start running near shore in mid August and this lasts around 6-7 weeks -- I usually fish Montrose harbor from the pier but skipped last year. The fish we catch are anywhere from 28-38 inches. The earlier in the season, the nicer the meat. My friends did go last season and did very well although we've all become a bit concerned about eating 10 lbs+ of smoked salmon from Lake Michigan every year. You all consider eating it to be relatively safe?
After gutting our fish, we drop off at Hagen's and they brine and hot smoke it for us with a few days turnaround. (Hagen's will clean it for you if you like for a small fee -- they need the fish whole). The smoked salmon is delicious and love it in everything.
The largest investment for me is in the lures -- KO Wobblers, Glow Rattletraps, etc. at around $5/ pop at Henry's or the tackle shop in Niles on Dempster. These are easy to lose, however, if you get snagged on the bottom. You need a decent rod (an Ugly Stik from K-Mart works fine) with a good reel if you're going to use a lower lb. test line like 8-12 lb. (Of course, you need fishing licenses and a salmon stamp, available at Henrys and most sporting good stores.)
People should just head out in the late afternoons to check out the action at all the harbors once they start running. Whether you fish or not, it's a sight to see all the people out along the walls and pier, with several freshly caught kings on the concrete or in the grass surrounded by murmurs of admiration. Personally, I like to ice them down immediately in a huge coolor or bucket but a lot of people just throw the fish beside them and keep going.
I think the fishing is best and less hectic in the middle of the night -- midnight to 4 am although you certainly need to bring your own huge net in that case since there's less people around to help out. You just need one person who knows what they're doing to get you started. It's very addictive so just a warning if keeping your job (and stuff like that) are important to you.
There are groups on chicagolandfishing.com under the Lake Michigan forum who wait breathlessly for the first salmon of the season -- it's a reliable source to know which piers they're running at. A search will yield many threads that walk newbies through the process.