It's a bad habit of mine to read things out of sequence. So, even though I haven't read Moore's Tomorrow Stories Volume 1, I'll throw out a few responses to Volume 2 here, a 2004 compilation of issues from 2000-02.
[Perhaps it's deeply ironic that I have so little regard for sequence on a blog concerned with what Scott McCloud (echoing Eisner, I think) describes as "sequential art": but at least I read the panels in sequence, if not the books.]
Though I haven't read all of the America's Best Comics titles or series, I've sampled a number of them over the years, and it looks like Tomorrow Stories is where Moore tries his hand at writing for humor--though not always as successfully as one might hope. Splash Brannigan (animated "science-hero" ink splotch) and Jack B. Quick (pre-pubescent farm kid/ super-scientist-inventor) are mostly concerned with spinning humorous superhero narratives (see, e.g., the "perfectly formed 'manure circle'" that alerts Jack B. Quick to the alien presence in "Why the Long Face?"), but the "adventures" of First American and U S Angel are also clearly tongue-in-cheek. Even the more seemingly serious Greyshirt stories occasionally descend towards the merely humorous (see the Nazi-cockroaches marching in Swastika-formation), as do the Cobweb stories. Some of the stories in this collection, though, just seem to hit a wrong note, as in the entire Greyshirt story presented as a musical, Broadway-style number (random musical notes in the speech balloons and all).
Typically for Moore, many of the stories find one way or another to work in various schticks from the history of the medium (even Herriman's Ignatz Mouse makes a small cameo), some of which are entertaining enough. These stories, of course, have none of the extended effect of Watchmen, but it's important to recognize how thoroughly comics history continues to inform, and even structure, the works of some of the key comics creators: not only Moore, but Spiegelman (In the Shadow of No Towers), Ware (Quimby the Mouse; Acme Novelty Library--the big Pantheon collection, I mean), and Kim Deitch (see my comments on Boulevard of Broken Dreams, in a previous post). I don't think I'd call this kind of intertextual referencing 'obsessive,' necessarily, but it's certainly insistent, and it demands our attention, I think. I'll certainly keep thinking about it. (Jared Gardner's essay on "archives" in the 2007 "Graphic Narratives" issue of Modern Fiction Studies partly addresses this issue).
I don't have much to say about the artists' styles here, although it's interesting to see Dame Darcy's style in a couple of Cobweb stories: it's a style much more familiar from black-and-white "indie" comics, and it has a kind of odd effect in the superhero narrative: but then again, the stories in question are a) a fairy-tale pastiche and b) a far-future frolic--both stories where the style doesn't really clash with the content. One wonders what the Greyshirt-Cobweb crossover would have looked like if half or all of it had been drawn by Darcy...