While I'm playing through the campaign, I'm using two methods. For one I'll follow the printed rules and continue using my Hobbits deck for the entire thing, but I also want to play the quests with thematic heroes and decks that fit the timing of the quests.
Here is my 2nd option thematic deck for The Road Darkens. I haven't looked ahead at any of the quests or encounter cards, (should get the box in the mail tomorrow), so I didn't tailor this to the quests specifically. I also really just wanted to use Gandalf.
I went with Allies that represent the Fellowship as best I can. Longbeard Orc Slayer is my stand-in for Gimli, while Northern Tracker and Son of Arnor represent Aragorn. The Elves represent the time in Rivendell and Elrond's Council. Bill the Pony for obvious reasons. I think this is a good mix between questing allies and combat allies.
Gandalf and Sam are the main actors, and Master of the Forge I hope to get immediately, so I can start finding my wealth of attachments. Hoping to be able to lower my threat and allow Pippin and Sam's abilities to be useful, but I'm worried with using Gandalf, those won't come into play much.
Also, I'm planning on using the Frodo Baggins from The Black Riders as my Ring-Bearer.