best bookshelf speakers for < $2000?


I have Studio-20 V5s on stands right now for my living room 2.0 music system and, while I like the sound, I need more bass extension.
I don't want to add a sub due to room clutter concerns.   So, I am looking fro an upgrade from my Studio20s.
I have been looking into towers but now am thinking, why not stay with sand-mounted speaker since I have the stands already.   This is for 2ch music only.  My amp is Emotiva UPA-2 SS amp.

Would I do better to go towers or go higher-end bookshelf speakers?


The towers I've been looking at have been 
Salk SongBirds/Towers
Ascend Sierra Tower
Silverline Prelude Plus

Thx.
albireo13
Well I think I will stick with bookshelf speakers. I will likely end up in a smaller room and think I can get te more articulate, intimate sound from bookshelves. 
My budget is $2000  my short list includes: 
Nola Boxer 2
Sierra-2
Vapor Breeze
Salk 1801


Any other good suggestions?
lots of great monitors at that price; Merlin, ATC, PMC, Aerial, PBN, PSB, Dali...too many to list
Honestly, you should put the Proac's in there.  Their new stuff is very nice.  
For a FLY-UNDER-USUAL LIST sleeper/wild card standmount candidate that is a "contender" and no "pretender" in your price range (+/-)for "new" speakers:     JMR (Jean-Marie Reynaud) “Bliss” Loudspeaker

check out the stellar reviews : very efficient   and easy to drive.

http://www.stereotimes.com/speak083010.shtml
http://www.amherstaudio.com/?page_id=42

NEWEST MODEL ON SALE in AGON:  

https://www.audiogon.com/listings/monitors-jm-reynaud-bliss-silver-monitor-speakers-free-shipping-20...

I've had a pair of Revel M106 for a little over two years and they have great bass response for a small speaker....I use a sub but run them full range.   At night I turn the sub off and the bass is still very satisfying.  They sound like a much bigger speaker without ever sounding boomy or bloated.  With a good sub they make for a great 2.1 system but I could easily live with just the two speakers.   I should note that I'm driving them with a 40 watt tube amp and they kick ass in my 17 x 15 room.  I have owned many high performance bookshelf speakers over there years and these are one of my favorites.