Anatares is exactly right! Good advice all around!
I found a substitute yarn for the Mara Shawl just yesterday by checking in on Ravelry. Go to the page for the knitted piece....click on the number of projects....when you're there, click on YARN IDEAS. It will tell you ALL THE YARNS other people used. You can click on each yarn category shown that others used, and see how the projects turned out, and read what the knitters said.
If you've come to the point of entering all your stash in Ravelry, the YARN IDEAS will also tell you if you have some of these yarns, too, and how many skeins you have! LOL! It told me I had 8 choices in my stash, but most of them were 2 balls, not enough. But I did have two stashes that were okay quantity! I chose one of them and cast on last night!
I also read what the other knitters said about this yarn choice with the Mara Shawl. I'm glad I did, because one knitter totally disliked her fabric (too compact) with the US 8 needle. She re-knit one skeins worth of yarn using the US 9 needle. She said the fabric created has more drape, and I know exactly what she means.
On the surface of it,.all the projects LOOK wonderful....but "drape" can't be photographed. You feel it when you handle it.
Anyway, using Ravelry's resources are a huge advantage! It's certainly helped me!