Bookshelf vs Floorstand speakers for HT????

If it is primarily HT, I would definitely go with bookshelf/monitors. Since you need Sub-woofers for HT anyway, why pay for redundant capability in your floostanders that you will be crossing over to sub-woofers anyway? Not only that, but you can usually get a higher quality bookshelf/monitor since the designer can concentrate his/her efforts and material expense on the mids and highs -- and you'll get higher quality lows because it costs $$$$ to get floorstanders that do bass well. I'd rather have a higher end bookshelf/monitor than a mediocre floorstander. Again -- why do that if you're just going to cross the bass over to the sub-woofer anyway? You can save that money, eliminate the redundancy, and end up with a better system by going with bookshelf/monitors and sub-woofers. But, don't skimp on the sub-woofers.

The deal there is that you'll get a potentially better dynamic (even crossing over to 80hz/small) using the 60's because of the extra bass driver, or more drivers! Why?...more emphesis on the affected frequencies, cancellation of distortion between 2 bass drivers, reinforcement of transients, more efficiency, etc.
The 20's, if I'm not mistaken, have 1 midbass (typical monitor), and the 60's have 2 midbass woof's, yes? All things equal, you'll have a bit better dynamic ability with more drivers. Again, all things equal. This advantage is certainaly more afforded, the bigger the room, etc. In a setting that's a smaller space, the 20's will sound more dynamic and powerful than in a larger space.
Also, the 20's "roll off" higher up (even though your processor rolls off bellow the "small setting") than the 60's, which will probably have more bass energy pressent bellow the "cut off" nonetheless. This is more noticeable in a small room, and less desireable often. In a big room, probably a benefit to reinforce what the sub's putting out bellow 80hz, etc.
Basically, in a larger room, the floor standers will sound sronger, while the 20's will be better suited (more than enough if set up right) to smaller spaces.
Yet, get either set up for proper coupling with the room, cross em over right, and you'll have good dynamics (If you don't treat acoustics right, you'll need to sit proximally closer with those designs, so you hear more "dirrect sound" vs. reflected...trust me.)
Good luck

I owned both the Studio 60's and Studio 20's. In my opinion, the Studio 60's had better midrange, as well as better bass. However, the Studio 20's are still nice speakers and for your application would probably do the job. Don't forget to factor in the cost of stands if you need them.

I have the 60s in my HT setup and definitely heard an improvement when I switched the fronts to large vs small. The cost of a good second sub will be more than the cost of going from the 20s to the 60s and give you better overall sound for both HT and music IMO. The footprint will also be the same as you need stands for the monitors and will add to the cost.

with all receivers and processors , when you set a large speaker to small, the sub is more active, if you set the speaker to large fronts the towers do some of the load from all channels aswell as the sub, but if you have a reciever or a processor with individual crossover adjustments, you can set all speakers as small and asign the proper crossover to each channels ability, I happen to like this feature but this is only optimal when configuring all small speakers in the set-up..just my opinion...I also think that some movies are great in 2 channel, but alot need 5.1 or more to really get the WOW. I do agree that bookshelfs are the way to go, but make sure if possible that you can safely run down to 80HZ, as this is somewhat of a standard in movie encoding.