Yeah, I'm really wishing we had more sort options for bookmarks (and you can't use the URL hacking trick for that, I tried.)

I think with the tumblr likes I used the "reblog first, tag later" strategy, because Tumblr actually does let you mass-tag your own posts! So I reblogged everything, and then came up with a list of tags I wanted to use, and then used the mass-tagging page to do one tag's worth of posts a hundred or so at a time. It went a LOT faster. (I was reblogging to a sideblog that I had warned people not to follow, so it didn't matter that they weren't tagged when they were first reblogged.)