<font color='#000000'>Both types have their virtues and vices. Bookshelf/mini monitor speakers usually image very well due to the smaller front baffle as opposed to towers. A smaller baffle will generally cause less diffraction. Another advantage of a small speaker is good driver integration, even in very small rooms or for nearfield listening. That's a plus if you must sit or prefer to sit close to your speakers.
On the other hand, floorstanders generally produce better bass and will play louder due to the greater enclosure volume. You may find that they are more dynamic, ie more able to cleanly reproduce the louder passages of a soundtrack or song. Also, if you go with bookshelf speakers, you'll have to budget in the cost of some decent stands, where naturally most towers won't need stands.
That said, both are viable choices. Maybe it would be helpful if you would describe what you plan to listen too a bit more. If you like to watch a lot of DVD movies at commercial theater levels, you better go with towers, or else budget some cash for a good sub (actually, you should do this anyway, if you can). If your tastes run to small scale acoustic music or pop, you may be able to get by with something a bit more compact.
I agree with Mr. dB that overall towers may be the most practical way to go, but the best advice written here is to let your ears be the judge.</font>