Lando, I realise that my usage is "uncommon" -- I rarely maximise my windows, and I have less than 1080 horizontal pixels to play with. In extremely urgent cases, when I absolutely positively have to see a full web site e.g. for my work, I'll turn the screen into landscape mode (then: 1920 pixels), but changing screen resolution in Windows 7 isn't an instant action. According to W3, the most common screen resolution is 1366x768, so that's about 300 pixels more than I have.
Does Opera 31 have something similar to small-screen-view? I don't mind visiting certain sites in "mobile mode", e.g. online forums.
James, I use my screen for work, and I work on MS Word documents, and documents are typically not in landscape, so it makes more sense to use an 1080x1920 monitor in portrait than in landscape (using it in landscape is like working through a letterbox -- can't see an entire page).