I disagree with OPs description of what kind of raid Karazhan was (Pretty sure Blizz has said that ToT is in fact their biggest raid ever in terms of raid-size) but I'd love another raid like it. It was anything but linear, having lots of extra rooms that didn't really serve any purpose to the actual fighting, but it made the tower seem more real. Instead of just having a hallway with a boss at the end there were several rooms at the sides with mobs you'd never go for unless you're farming rep, and then there was huge areas (stairs next to attumen) that was there just because. Loved how they used that space for the wotlk pre-event boss too.
You could go around exploring areas of the raid just because it was a fun place to be, and having so many optional orders in which you killed bosses was really neat.