May's recommendation: Silverlock, by John Myers Myers.
From what I remember of my one encounter with it some years ago, nobody in their right mind would imitate Pilgrim's Progress. Yet that is what John Myers Myers has done here.
Mind you, he's chosen to imitate Pilgrim's Progress in a setting populated by a never-ending panoply of characters drawn from myths, legends, ballads, literature, folktale, tall tales, you name it, it's in there -- which is probably why I like it.
The setting is the Commonwealth of Letters, where one may find oneself agreeing to help Janet go after Tamlane, who's in the thrall of Nimue, wife of Gwynn Uriens MacLir -- have fun counting the sources Myers hits in just that one episode. In the Commonwealth, individuals, places, and objects from wildly disparate tales rub shoulders with one another, partly because of the archetypal nature of the geography. The forest of Broceliande isn't just Broceliande itself; it is, in a sense, all forests. Watling Street is all streets, and the Long River is all rivers. That's why you can run into Puck and a nineteenth-century Louisiana swamp doctor shortly after leaving Robin Hood and his men to their pursuits.
The protagonist is one A. Clarence Shandon, nicknamed Silverlock for the streak in his hair. He comes with a caveat that you won't like him very much to begin with; that's part and parcel of the Progress-y aspect of the book. The novel kicks off when the tramp steamer he's on sinks, leaving him drowning in the sea, and his narration makes his state of mind clear:
I wasn't able to credit my own non-existence any better than the next man;
what I had lost was a healthy abhorrence of the state. It had not dropped from me because of
any particular shock or misfortune. It had moulted from me year by year, for all of my
thirty-five, to leave me naked in apathy.
So you start off with a protagonist who can't even really be bothered to keep himself from drowning. Fortunately for him, somebody else takes on the task of saving him, and of kicking him in the ass until he starts to develop some amount of interest in the world around him.
Side-note of geekery: though not a ship of the Commonwealth itself -- it comes, like Shandon, from the ordinary world -- the ship he's on at the start is called the Naglfar. Yes, THAT Naglfar. The one from Norse mythology, made of dead men's nail clippings, which will sail the seas when Ragnarok comes. You're all of half a page in when the geekery starts.
To return to my point, the novel is about Shandon's progress, his development from apathetic (and asshole) stranger to a worthwhile human being. He isn't the most compelling character I've ever read about, but just when I was starting to think that, for all his improvement, he still didn't really do much for me, he got into the end-sequence of the book, where he really got to do some interesting things. (I mean, nothing like a trip to Hell to make you think about who you are, and why you should care about yourself.)
Silverlock's tour through its variety of narrative materials can be both a source of entertainment (playing spot-the-reference is fun!) and a source of irritation. There are times, I must admit -- such as when Golias, Shandon's main companion, gives a synopsis of where he's been since Shandon last saw him, which often reads like an exercise in name-dropping -- when I find myself wishing there weren't quite so many random cameo appearances. Like, what's the point of seeing Doña Ximena on the road? Does she accomplish anything more than cramming a reference from El Cid into the novel? (On the other hand, the entirely gratuitous Odin walk-on had me bouncing with glee, 'cause he was carrying Tyrfing.) But if you're the sort of geek who can appreciate such things -- if you giggle at the thought of Golias standing up in Heorot and singing, in properly alliterative Norse verse, the saga of the Alamo -- then, you, like me, may be convinced this book was written just for you.