I have to start out by saying that I am a Clive Barker fan. Don't know what that says about my psychological makeup - and I probably don't want to know. All I can say is that he is the only horror author whose writing has ever actually frightened me so much that I had nightmares (I can probably count the number of nightmares I've had in my life so far on one hand, so I guess that's quite an accomplishment.)
I've never read "Sacrament", so I can't give a specific recommendation for that. I think I've got it around here, so I should probably try to find it and read it. And I tried to read "The Great and Secret Show" but had to put it down because he used Simi Valley (where I grew up) as a location, and really screwed up the geography. Yeah, I know, literary license and all that - but that's one of my pet peeves about writing: if an author is going to name a real location in a book or short story, use the real place. If he or she wants to make a place up, make a name up too. That's just me, but it made the book unreadable for me.
Now, on to what I have read. "The Books of Blood", which are the first Barker I read, are a bit uneven I suppose, and deliberately shocking sometimes. But many of those stories are really quite interesting. "The Damnation Game" carried me through but wasn't really anything special. "Weaveworld" was much better, I think the first of the novels where Barker creates a unique world.
"Imajica" is very long, and I never have read the last hundred pages or so - but I think that was because I did not want the book to end. It is a very, very long book - it sometimes comes in two volumes, as a matter of fact - and probably a bit self-indulgent on Barker's part, but the world he created for that book is so fully realized that the length didn't seem to matter. I was so into reading it that I carried it on a trip to Disneyland and actually read every time I found myself waiting in a line to get on a ride.
"Coldheart Canyon" is a bit of a departure, in a way, but it is also vintage Barker. I really want to read it again, I liked it so much. It takes place mostly in a mansion in the Hollywood Hills, and is just amazing. My favorite of Barker's novels, though, is "Galilee". It has to do with a very long-lived (but not necessarily immortal) family. I don't even want to try to describe it - it has to be experienced.
Goodness. I didn't mean to go on so long. I think the bottom line on Clive Barker's writing is that he sometimes goes for the gross-out or the shocking a bit more than I am comfortable with, especially in his short stories. But - and it's a big, significant but - he is also a wonderfully imaginative writer who deserves a look beyond the gore and the outrageous.