Need a Speaker Recommendation

So, I'm putting together a secondary system composed of used components. My budget for the speakers will be in the $400-$700 range. The speakers will be paired with a Rotel rsx-1056, which I believe produces 100 watts X 2 into 8 ohms. So far, I've been mainly considering B&W speakers because I am most familiar with them (leaning towards 603 S2 or 602 S3). However, I'd like to hear any recommendations you guys have for an alternative speaker that can be found used in this price range, and pairs well with the Rotel(any brand, bookshelf or floorstander). The room is square shaped and approx 18' X 18' with a very high ceiling. I appreciate any advice you guys have--and please take used availability into consideration. Thanks.
As I have before recommended.. I recommend again a pair of Vandersteen 1c's (or 2c's used). The 1c's are, for the price, quite amazing --- full bodied, pretty much full range. They play really well at low volume. They image well. Actually, they have no real flaw (given the price point). By this I mean that some other $700-$900 speakers may possess one or two attributes that beat out that attribute in the Vandys... but then have flaws as well. The Vandersteens do everything --- you name it --- everything well (again, at the price point) w/o any real shortcoming. You can get amazing sound out of these speakers. An awesome value. In fairness, some may not like the looks of the speaker --- but no one can impugn the sound.
2nd to Vandersteen 1c it speaks for itself. They will be used for $400...500.
I too recommend the Vandersteens for the budget that you mentioned. I sold my Vandersteen 2C to a guy here in the Bay area, CA on the very low end of your price point and since have seller's remorse.
Yup. Yup.
Agree with the vandersteens; i would also strongly recommend polk lsi9s.
A consensus is building here.
A pair of used Vandersteen 1Cs is one of the best bargains out there. I've owned them twice and loved them both times.
Only issue with Vandys is that you can't take them apart to look at stuff, and cats can (and will) rip the crap out if 'em. I had some new 1Bs and after my cats messed them up I sent them back to Vandy to have them recovered and tightened up (I called Vandy and actually inadvertantly got Richard Vandersteen on the phone...asked if since they had my speakers could they please upgrade them...he bit my head off...said something like "the newer ones have EVERYTHING improved so NO WAY DUDE"...a treasured audio moment). Sold them to a friend when they got back as I couldn't stand to see them subjected to feline abuse again. The end. Oh wait...also they sounded AMAZING.
Thanks guys, that's really eye-opening information for me--I've never heard these speakers but I will make it a point to go find a pair to audition now.

Wolf_Garcia: thanks for the info--my gf has an annoying cat named Zippy that will definitely tear them apart so that's really good to know
After checking out these speakers briefly on the internet, I'd like to know if there's any other speakers anyone can recommend as an alternative option? While I'm sure the vandy's sound great, they look like they may not fit in with my current living room setup, and another option would be nice to have anyway.
Check out the Neat Petite III monitors currently listed for sale here. I have no affiliation to the seller or Neat but they are a really cool little monitor and a lot of speaker for the money. They would grow with you when you decide to upgrade from your Rotel.

Also in your price range worth checking out is a pair of used Green Mountain Europas. GMA has a great reputation.

Another option might be to pick up a used pair of Magnepan 1.6 panel speakers. Close to your price range and an amazing bargain for under $1,000. You won't be hosting a rave with you amplification but if your decor will tolerate them, that would be an interesting listening experience.

My personal recommendation would be to call Ty Lashbrook at Tyler Acoustics and tell him what you want to do both now and in the near future. He has a trade up plan so you could start out at the entry level with him and grow as funds allow. I once had some of his Taylo monitors and boy were they fun. I have since "upgraded" a dozen times but never has the bang for the buck been better than when I had some Tylers and a Cary SLI80.
That's an option I will definitely consider. Thanks.

Btw, I should clarify that when I said they may not fit in with my current living room setup, I specifically meant that they look like they may just be slightly wide to fit into the slots I have for them in my entertainment system furniture, but I'm not completely sure yet. Also, there's a girlfriend-factor...she may not approve of the appearance, so you know how that goes.
I use a pair of "Stereophile recommended" Silverline Preludes bought from Ebay for half the original price (with shipping I think they were under $500)...and they sound great (kind of need a sub I use a REL 10" with 'em).