As a child in the 80s, my aunt gave me an illustrated fantasy book full of short stories. It was an 8-1/2 by 11 book, IIRC, and the illustrations were in full color, taking up half of the page space. The one I remember most vividly involved a giant eagle and a phoenix having some sort of battle, but there were a few other stories, too. The illustrations were fantastic (or at least I thought to at the time), and I've never seen another copy of this book since. I know my details are thin, but I'm hoping someone might remember what this book is.
Is it perhaps The Kincaid's Book of Wizards, Giants, Trolls and Magic?
I had that one during the same time frame you're talking about and a lot of the details seems to match.