Nearly impossible for Europe, but better for domestic US
Like others I had tried booking to Europe for this summer in January. No luck on standard. I was unable to get a single ticket from IAH to any city in Europe during summer on CO. I just lucked out on Hawaii during spring break, which I took. But it is virtually impossible for Europe. Domestic USA is better except for peak periods and for popular destinations. Of course Easy pass is always available to everywhere anytime.