I've been reading up on blanket cleaning since I have a big stinky one hanging on my horse's stall that I need to deal with.
I've basically come to the conclusion that I'm just going to pay a blanket place to clean it for me! It's only like $8 and they'll use all the proper cleaning solutions (not my regular ol' detergent that may irritate my horse). Also, they insure that it is completely dry before folding/packaging it up. If your blanket is moist AT ALL and you store it over the summer...it could grow up some mildew/mold/funk.
If you do decide to wash them yourself...do one at a time! Also buy some sort of "blanket wash solution" or use Baby laundry detergent. If you want to save your washer from wear & tear (& hair!) then take to to a laundromat and use an oversize washer.