I want to 'carry my library with me' like the ad says

I do think they will add tags or folders soon and that will make it easier. But I have some books I already read but which I might want to read again, and I have some I haven't read. I also have some I have read that I do NOT want to carry around with me
I am really trying to prune the 'junk' out of my collection and use the Kindle for beloved books I have read already and new books I have yet to read. But that still will be a fairly heft collection
I don't see how it could take more than overnight to charge and load, but I could be wrong about that