Having just scoured my way through the whole of Bone, and taken my handle from From Hell, both of which had every issue of the comic put together in catch-all collections, I wonder why so few other comics go the same route. TPBs usually cover just 6 or so issues...which is kind of a gyp really, unless those issues were a limited run to begin with.
I'll admit, I'm not a comics collector. I just don't have the time to run about after my favourite titles, when I don't even know if my store's going to carry them. Add to that the fact that Vertigo, which has carried most of my favourite titles, prints on paper that makes public toilet loo-roll look as lavish as precious hand-rolled Ancient Egyptian Papyrus, and I become a TPB man by default.
I also like to hurtle through stories headlong, without it being interrupted for a month come page 24.
I think if more comics went the Bone route, then that would be another step towards breaking open the industry even wider.
If we're talking about comics which had 60+ issue runs, then just go the Sandman route and Absolute them in two or three different books.
I also think that most people who read comics could stand to gain a bit of muscle-mass, and lugging about a 1200-page graphic novel will definitely help you with that...

Anyway, which series would you most like to see compiled together?
I'll start the ball rolling with Lone Wolf & Cub.
