I would really like to be able to create multiple wishlists.
For example, I might have a wishlist on which I'd put games I'll definitely buy, another for serious interest, one for free-to-play games to check out. Maybe one for DLC, another for soundtracks, hell, why not one I could set to private for games I'd like to gift others. You get the idea, just so I don't have to have a huge list of games and DLC and soundtracks aand whatnot all in the same place.
Manually managing a wishlist beyond ten or so titles is just cumbersome, even with ranks and sorting. I always think in "blocks", as in categories I described above, but having to put every title in the correct spot manually is both annoying and I'd always have to check which number is the current correct one.