Even listening to classical music there is a significant amount of personal preference that goes into your decision. While we can give you advice, you really have to hear the speaker for yourself. I have listened to classical music on so many systems, many of which I did not like, but that doesn't mean that someone else would not like them.
My criteria is similar to yours, but there are a few other things to consider. One is dynamics. You didn't mention this, and perhaps it's not terribly important to you. Classical can be very dynamic, but if you listen to mostly chamber music, then that really isn't an issue. Another critical area is bass reproduction. While you didn't mention this, I think this is probably important, because you did mention soundstage. I find that you really need good bottom end detail to establish a context for the soundstage (a place for the other instruments to exist).
Lastly, you should consider, where you want to sit to listen to the orchestra. I don't mean in your living room, I mean in the concert hall. Do you want to be in row A? I don't. And I've heard some very highly regarded systems that put me in row A (or maybe I was in the viola section). It was too close to the instruments and I didn't like it at all. I prefer to be in row K. (I still can't get those tickets for the Baltimore Symphony--but I can in my listening room).
Now I can only offer you some advice as to what I've listened to (a small subset). I have listened to older Klipsch (La Scala's and K-horns). Very dynamic and excellent tonal accuracy. Significant problems are limited frequency range, poor soundstage, poor depth. These would not meet your criteria.
B&W 801 Nautilus. These are very good. In my opinion these are extremely well rounded speakers. Great dynamics, good bass, good imaging, good soundstage. Not the best on depth--low level articulation is lacking a little bit.
Revel Salons. I really liked these. They have great depth, articulation, soundstage, bass. The only thing I have to caution you on here is that I only listened to these for a few hours, but was very impressed. I think if I were in the market for speakers I would spend a lot more time listening to these.
Martin Logan Monoliths. I own these, so I'm most familiar with these. Most people know the benefits of electrostatic: imaging, soundstage (even without good bass), (vocals are amazing), coherency, low level detail. They are usually aware of the downsides: poor dynamics, poor bass (and as a result poor depth). For me the bass was really a problem. I couldn't get a convincing orhestra without convincing bass. I therefore modified the speakers with Focal Audiom drivers, biamped the sytem, and the result was excellent bass and dynamics that it desparately needed. I can't really recommend these speakers without the modfications--and wouldn't really recommend doing these mods--unless you're really into DIY. Their new line might be something to consider. I have only listened to the Prodigy speaker twice and both times I felt it was not set up properly--so in short--I really haven't heard that speaker.
I think I've used up enough space here--and hope it's been helpful.
