I guess there are 3 systems that stuck out the most in my mind.
One was a Meadowlark Kestrel/Rogue Audio Tube combo and Myriad CD player. That was the first system that I heard that made me realize why people get so into hi-fi "oh this is what it's all about!"
The 2nd "great" rig that I heard was pair of Joseph Audio Pearls driven by a pair of McIntosh 1200 Monoblocks (Mac pre and CD player). I actually really didn't like the sound that much, others in the room did, but it was interesting to see that a really expensive system can't please everyone.
I think the rig that impressed me the most was a RedRose set-up at Mark Levinson's store in New York. The whole thing was a fraction of the cost of many stereos that I've heard and really sounded great (Affirmation Integrated, Classic speakers, Rega 3 turntable). Not cheap, but simple and better than most systems out there.
If I was to put together an ultimate system, I'm not sure what it would be yet. I'm still discovering new products and learning as I listen more and more. I guess I just wanted to see was what people's personal references were when they choose the equipment that they have.