Let start with the simple stuff:
Floorstanding speakers will give more bass than bookshelf speakers, but, for a room where you want to have small speakers you can have really good sound from a small cabinet. Here is a non-controversial example. Kef LS50 bookshelf at £ 799/pair are clearer and better than Kef Q950 at £ 1199 even though the bigger cabinets will give more bass and go louder. To have the clarity of the LS50 and the bass you would need to go up to the R500 or R700. Clear? If not drop me an email with questions or call in to hear the difference for yourself.