According to this onion catalog I received they list some for our area. (Ohio) Here they are and storage time. Big Daddy 4-6 mths, Copra 10-12 mths, First Edition 10-12 mths, Red Zeppelin 6-8 mths, Sterling 6 mths. According to the catalog Walla Walla is only 1 mth. Hope that helps. I got this free catalog from Dixondale Farms. Info for planting time, types of onions and what grows best in different areas. I think they deal mainly with onions. Alot of useful info.
You're right. According to catalog Ailsa Craigs also store for about 1 month. I am looking here and ther is something called Ringmaster and it lasts 4 months. Ya sign up for the catalog. I think you will find it useful. I am sending you the site and you can even check it out over net. www.dixondalefarms.com
I have good luck with Yellow Spanish onions. They store better than any thing else I have grown. Big Daddy onions keep well, but not as good as the Yellow Spanish.
Walla Walla won't store hardly at all. If refrigerated and they will last a couple of weeks. Their best use is for early and sweet fresh onions.
Successful onion storage depends quite a lot on conditions. If the humidity is high, they won't store well. Here in dry Utah, they store pretty well in a mesh bag hanging in the basement. My basement has an almost steady temperature of 68--70 degrees and a relative humidity of 40--45 %. I will have some onions keep until May.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-