I keep my soil mixes in big giant Rubbermaid storage totes labeled as to what they were made for, seedlings, veg, flower, etc.

My only issue is that now we're getting into the freezing time of year so I let them dry out completely so I can still scoop some out even when it's 10 degrees out on my porch! Then they do have to be re-hydrated in the bathtub, but whatever.