DC's crossover collection schema in the New 52 has tended to go one of three ways. For crossovers between two books (Stormwatch/Red Lanterns, Resurrection Man/Suicide Squad, etc.), DC collects the crossover issues from both series in both titles' collections, which is good if you just read one series and negates having to "trade-jump" between books.
For crossovers with a "main" title accompanied by tie-ins, DC tends to collect them like this:
• Batman Vol. 3: Death of the Family - Batman #13-17
• Joker: Death of the Family - tie-in issues
Each of the tie in issues (Batgirl, Nightwing, etc.) are then also collected in their own individual series collections.
What's good about this is if I'm only interested in the very core story, I only need pick up the Batman book. If I'm generally interested in "Death of the Family," I could pick up the Batman and the Joker tie-in book. And if I already collect all the Bat-titles, I could pick up Batman and the other individual series, still be able to read the tie-ins, and not have had to buy anything extra to follow the crossover. Seems like a win.
Finally, when a crossover has no "main" book, however, but rather the parts are split between a couple of titles equally, the collections tend to look like this:
• Green Lantern: Rise of the Third Army - Green Lantern #13-16, Green Lantern Corps #13-16, New Guardians #13-16, Red Lanterns #13-16, Green Lantern Corps Annual #1, pages from Green Lantern Annual #1
• Green Lantern: Wrath of the First Lantern - Green Lantern #17-18, Green Lantern Corps #17-20, Red Lanterns #17-20 and Green Lantern: New Guardians #17-20
• Green Lantern Vol. 3: Rise of the Third Army - Green Lantern #13-20, #0
• Green Lantern Corps Vol. 3: Rise of the Third Army - Green Lantern Corps #15-20, Green Lantern Corps Annual #1
• Red Lanterns Vol. 3: Rise of the Third Army - Red Lanterns #13-20, #0
• Green Lantern: New Guardians Vol. 3: Rise of the Third Army - New Guardians #13-20, #0
Here, the first book collects just the "Rise of the Third Army" storyline and the second collects just the "Wrath of the First Lantern" story; and again, the individual series are collected alone in their own books.
What's good here is that, if I'm just a casual Green Lantern fan, I can pick up the two crossover volumes and get a full story in just two books. However, if I read the individual Green Lantern series, my choice is four collections, all of which only collect part of the crossovers -- so, I imagine, I'll have to flip back and forth between four collections to get a comprehensive story.
And also, the individual collections start coming out in October 2013 and finish in January 2014, so a Green Lantern fan would essentially have to sit on these books for four months until they could read the story in full.
Again, this is pretty fair -- whether you read all the series, one of the series, or just the crossover, DC has a solution for you that means you don't have to buy more than you should. Only, the reading experience might be awkward, and it might take awhile before you can read the books.
Real difficulties begin to arise in situations like with the "Young Justice" group "Culling" crossover:
• Culling: Rise of the Ravagers - Legion Lost #8-9, Superboy #8-9, Teen Titans #8-9, Teen Titans Annual #1
• Superboy Vol. 2: Extraction - #0, #8-12, Teen Titans #10
• Teen Titans Vol. 2: The Culling - #0, #9-12, DC Comics Presents #12
• Legion Lost Vol. 2: The Culling - #0, #8-16
Once again, there's a main book and then there's individual books, which is good. However, the Teen Titans annual, even given that it might be pertinent only to "Culling," is collected only in the main Titans book -- this might pose a problem for some completists. See also the "Throne of Atlantis" crossover:
• Justice League Vol. 3: Throne of Atlantis - Justice League #13-17, Aquaman #14-16
• Aquaman Vol. 3: Throne of Atlantis - Aquaman #14-16, #0, Justice League #15-17
The Justice League trade contains the same issues as the Aquaman trade (as solicited by DC) and the Aquaman trade contains a handful of the Justice League issues, so the Justice League trade would seem the one to read. The only difference is the Aquaman trade includes that book's zero issue -- so here again, for completists, in order to get the full Aquaman experience a reader would have to pick up an entire trade only to get one issue's difference.
How did we get from the good to the trouble?I think the Green Lantern books have it right, in that everything that appears in the main collections also appears in the individual collections. Culling is closer -- in both the Culling and Green Lantern examples, I don't much like to have to "trade-jump," but I don't see a better solution; the Teen Titans Annual is a sticky widget, but probably unavoidable.
For someone with no interest in the crossovers at all, I doubt an individual collection of Legion Lost or Red Lanterns will read well, ducking in and out of the crossovers, but that's probably what someone who was only following an individual series on its own would want anyway, whether the reading experience makes good sense or not.
With Justice League and Aquaman, I sense on DC's part a reluctance to 1) collect the very same issues in two different books, or 2) to make a true crossover trade, like Justice League/Aquaman Vol. 3. The latter would be awkward, but it would work -- the eight issues collected in the individual Justice League trade would expand by one to include Aquaman #0, and the Aquaman trade could go away entirely.
Or it could be Justice League Vol. 3 and the Aquaman Vol. 3 label could be saved for issues #17 and on of Aquaman, or the book could just be called Throne of Atlantis (like Culling), still collect those nine issues, and both Aquaman and Justice League would continue with their third volumes later.
Take this pre-New 52 example:
• Green Lantern: War of the Green Lanterns - Green Lantern #63-66, Green Lantern Corps #58-60, Green Lantern: Emerald Warriors #8-10
• War of the Green Lanterns Aftermath - Green Lantern Corps #61-63, Green Lantern: Emerald Warriors #11-13, War of the Green Lanterns Aftermath #1-2
In essence, Green Lantern, Green Lantern Corps and Green Lantern: Emerald Warriors didn't get their own invidual trades there, but rather they were combined in a crossover collection. That book finished Green Lantern, but then the last issues of Corps and Warriors were included in another "combination" collection that also included Aftermath.
I understand why DC doesn't want to go this route any more, giving each individual series their own sequential, numbered collections, but neither do I think any of us want an Aquaman trade for only one issue we can't find outside a Justice League trade.
What crossover books have you bought in the New 52? What do you think the problems and solutions for crossover collecting are?