What should I put on my wall?

I have a large wall in my living room that I want to fill with new prints and I am thinking that typography is the way to go.  One small problem though... there are so many lovely prints out there that I don't know which to choose.  Any suggestions?

I love this 'Bake more cake' letterpress print, from Print for Love of Wood via Folksy.  The muted green is particularly pretty, but I wonder if it belongs in a kitchen rather than a living room.

I like the simplicity of this design, by Graphic Anthology via Etsy.  Definitely top of the list.

This 'Happiness Manifesto' makes me very, well, happy.  Full of advice that I would do well to take note of, it's from Sugar Rush UK via Etsy.  I love it very much, but it's perhaps too similar to the Aardvark manifesto that I already have gracing my living room wall.
Finally, I saw this 'Just be' framed print in the window of Oliver Bonas in Cambridge and fell instantly in love.  It's £60 though... gulp.

One annoying thing is that, although the prints above all match each other very nicely, none of them go with my living room, which is presently dominated by a large purple sofa and red cushions.  I'm wondering if it's time to change the colour theme as well as the pictures.  Or is it ridiculous to decorate a room around what I put on the wall?!