Man, you ought to go to Audiogon or Audio Asylum as they have really extensive discussions on speakers (just the way this place has for headphones).
For your budget and sound, the Vandersteen 3A Signature would be one viable speaker to audition. I have the Vandersteen 1C and this brand's sonic signature has some (but not a 100%) overlap with your criteria and your Senn 650 analogy (warm, lush, relaxed mids, detailed, mucho bass, decent high's). There are many (many!) other speaker brands to choose from, and many have a sound that is like what you describe.
I'm considering a move up from my vandersteen 1Cs but am after a different flavor -- something faster, with stronger mids and a better fit for rock. I've narrowed my list to Von Schweikert (VR2), Totem (Hawk) and Gallo (Reference III). All of these are in your price range ($2500), and get very good user reviews, but at the end of the day, you'd have to listen to any speaker to determine if it's your flavor.
- walk