If you want openness try the Vandersteen 5a they are the most open I found and have the biggest soundstage. They also have built in subs so you get true biamping and work wonders with tubes amps since the amps supply the mids and highs. I use quicksilver v4 120w and it is more than enough. I also upgraded to the 303/300 it is a improvement.
However the other part of soundstage is are the speakers positioned optimally. If not try pulling them out about a foot or two from where they are sitting if near a wall or next to things. I'm sure you have done this but just wanted to mention it.
However the other part of soundstage is are the speakers positioned optimally. If not try pulling them out about a foot or two from where they are sitting if near a wall or next to things. I'm sure you have done this but just wanted to mention it.