Fabric Depot is great, but they don't have 35% off every day, just once or twice a month. Though typically they will have something discounted at least 20-25% (usually certain fabric lines and they rotate them, check out their website
www.fabricdepot.com and their calendar will tell you what will be on sale.) There is a lovely shop in Lake Oswego (just outside of Portland) called The Pine Needle as well. I don't know of any others besides those two and one down in Beaverton whose name I can't remember, but I do recall it was a lovely shop. I don't get down there much as I am north up in Vancouver - we have two lovely stores here, The Quilter, and Art and Sew'l. The second has a small selection, but they are both nice shops. Have fun visiting, Portland is a wonderful city!
And Yes, Powell's is a great place to visit too! Really nice selection of crafting books!