Why would you want to?
OK, I'm old fashioned but I still think of "bookshelf" speakers as the ARs and KLHs of the '60s and '70s, often shown in ads actually placed in bookshelves.
But I believe you are actually asking about stand mounted (monitor style) compared to floorstanders.
Last point first, you mention expense but many of the stand mounts can be very expensive too, and even more-so once the cost of appropriate stands is added in. Just price the Magicos!
Considering sonics, to me the advantage of better stand mounted speakers is the openness from good dispersion and minimized cabinet colorations. But they either lack the warmth of musical foundations in the lowest two octaves or they include a "false" bass from a designed-in peak, usually between 60 and 180 Hz.
With proper design, good floor standing speakers can avoid the boxy, closed-in sounds and cabinet colorations to which you may be objecting. A few options have been suggested above and I would agree with Vandersteen, Audio Physics, Proac, and Merlin. I would add Duntech/DAL, Thiel, Totem, and Gallo. I'm sure there are others that I'm not so familiar with.
