I lived for that first weekend of the month, when DCCP and Justice League of America went on sale. Just about every other comic I got back then, aside from other 'team-up' books, felt like a substitute to make up for the fact that they only published those two titles once a month.
After a long gap following # 4, my first DCCP off the spinner rack was # 17, an awesome Superman-Firestorm-Killer Frost story, by Jose Luis Garcia Lopez, featuring 'frosty, mind-controlled Supes' protecting KF from Firestorm's blast(Stormy found a perfectly valid 'comic book logic' way to snap Superman out of the trance). The Deadman team-up in # 24 was another 'instant classic', that picked up from the end of Deadman's series in Adventure Comics, and wrapped things up nicely for him. The next issue was the beginning of the 8-page back-up of 'Whatever Happened To...' heroes not seen in quite a few years(best remembered for the Crimson Avenger tale in # 38). Even if it was a character I'd never seen/heard of before, like Rex the Wonder Dog, or Richard Dragon, they managed to make it worth reading.
Maybe the most memorable issue, aside from # 26 including the 'New Teen Titans' preview, was a 50th-issue meeting of Superman and...Clark Kent(which made the 1982 'Year's Best Stories' digest, just as the Sergeant Rock story from # 10 had for 1979).

I felt that in the last couple of years, things seemed to drag, and the book needed a bit unceremoniously with # 97, as the John Byrne 'reboot' meant the book had to go in mid-86, so no anniversary issue. That final issue, by Steve Gerber, was billed as having taken place 'before Crisis'...but, curiously, Gerber used Bizarro and Mxyztplk in much the same fashion that Alan Moore did that same month, in his two-part 'farewell' in Superman and Action.
I REALLY wanted a Superman-Jonah Hex team-up for issue # 100...but they did that eventually.

The best part of the 3 pack was the sometimes oddball stuff they'd stick in with the other comics. I've bought 3 packs with oddities in them like Black Goliath (in a 3 pack where the other two were early 90s books) and an issue of Marvel's adaptation of Dune. While we're on the topic of 3 packs, does anyone remember when First comics used this method? I remember a dollar store had a ton of 3 packs of First comics books (mostly 86-89 titles). I got as many as possible and it introduced me to a lot of new books I previously never would have discovered on my own (American Flagg, Nexus, Grimjack, Badger). Back on topic, I miss dialogue on comic covers. Though it was usually ridiculous hype, it made you want to know what exactly was going on in the comic to get to this scene.

Some of you other older comic book readers are more luckier than me from back in the day in the early and mid 1980s

Those Whitmans 3 comics in one bag that I saw at the grocery store when I was a kid, it was that one issue of Flash Gordon, Magnus Robot Fighter and the usual Donald Duck or Mickey Mouse comic.

Other than that, my parents would buy the regular single issues of Groo, Spider Ham, Alpha Flight, Elfquest or even G.I. Joe from the newsstand section at the grocery stores or drug pharmacy store. Even an issue of Cracked or Mad magazine back in my day when I was a kid.

Funny that the Whitmans bagged comics which was mostly consisted of Flash Gordon or Magnus Robot Fighter they were still being sold after the Flash Gordon movie was done showing in theaters. At the time, I guess the bagged Whitmans comics were just popular at at the time in the early and mid 1980s in out in the boondocks small towns grocery stores

I bought the Star Wars #7-9, 10-12, and 13-15 bags together in the summer of 1979 at some big U.S. mall knowing they were reprints of some kind. I'm pretty sure I had yet to walk into a comic shop yet, so I think these are why I've always felt those diamond style corner boxes and blank or crossed out UPC area mark a comic as a lowly 'not real' reprint to me. It still gets me sometimes when ordering an old Marvel online to get the direct edition when they show the newsstand issue (have learned to check for the stock photo footnotes now). I had some of what was in those Star Wars issues in b&w in thinner British weekly editions. Later they would reprint Doctor Who weekly comics in color in Marvel Premiere. I almost think of the British Star Wars as being the better editions to have anyway as they had a little bit of extra art not in the U.S. comics.

I had those Marvel Smurfs comics as well; I think there were only ever three published. So many others missed them and it's almost like they didn't exist for most collectors. Our shop owner was big on Donald Duck and it was only later comic shops I went into where I found anyone who looked down on stuff like that. Not a good idea to ask about any Scamp comics in a strange new comic shop where a bunch of guys in Lobo and Wolverine shirts are yakking about who they killed in D&D last night. I also loved Spider-Ham!

I saw a Superman Vs. Muhammad Ali tabloid with the Whitman label so I know they did that one. Funny they'd leave issue numbers off of some of the regular comic covers though.

There were a few different Whitman programs.  Whitman was owned by Western Printing & Lithography, who also owned the Little Golden Book line.  Whitman was their publishing division, for coloring and activity books and puzzles & games.  They marketed their own comics (under the Gold Key name and then under the Whitman name, when they were solely publishing via the bagged sets) in the sets and they had deals with DC and Marvel.  The DC books had the bullet logo altered with the Whitman logo, instead of the DC lettering.  The Marvel issues would only have the bar code replaced by a blank rectangle, where the UPC symbol would normally be.  Whitman also published some treasury editions of licensed titles at Marvel, including Star Wars, Battlestar Galactica and one or two others.

Whitman did their own distribution to stores and their salespeople would sell job lots of product to various stores, for placement in their toy departments (usually) or newsstands.  Their program went way back and by about 1980, they were only distributing their comics that way.  The DC program was in the late 70s to the dawn of the 80s and they moved a ton of DC titles.  Marvel was around the same time, but their program wasn't as prolific.  They may have had another distributor, as I picked up a bunch of Marvel sets of a family vacation to Florida, at a Stuckey's.  They were in bags, without logos, and definitely without the Whitman logo.

Charlton also had a program, circa this time frame, via Modern Comics.  These were mostly reprints of old titles, put out in grab bags.  they weren't as prolific as the Whitman program, as Western had a bigger sales force and relationships with retailers that went back generations.

I think there was even a pack of the three-issue 'Untold Legend of the Batman' as one of the last DC-Whitman tie-ins in 1980.
I can remember DC having both 3- and 2-packs(while Marvel only had 3). I remember being disappointed about a 'missing' comic, and my mom looking for the 'middle book' in the Marvel pack.

Out here in the wild west of Arizona you were lucky to ever find any bagged comics of any sort. They were usually found in K-Mart or Thrifty's drug stores where they hung on pegs wherever the store folks felt like putting them. You might find in the toy aisle or on end caps or in the audio/stereo department. And you would almost always find them torn open and the store won't sell an opened bag so you stood there in the store reading as much of the issues you could before your mom was finished browsing the store.