It turns out that there are two ways to do this (building on the comments):
-One is to print to file and use a pdf extension after setting the orientation to landscape at the relevant print options dialog. Normally, when exporting to pdf, mathematica chooses the best way to rasterize 3D graphics if you add an invisible polygon (triangle) as a texture somewhere in the plot (see Jens's relevant blog post). The benefit of this is that you may rotate, rescale, and change the graphics while still making sure the pdf won't be huge (there is about one question a week about why mathematica saves to enormous PDFs) and the images will rasterize. Sadly, this doesn't work when printing to file for some reason so I had to go through all the figures and rasterize them for this to work. And also, one needs to take care that the document stretches to the page properly (see this answer).
-The other is to write a LaTeX style landscape template for exporting to pdf and save the notebook as pdf (a nice tutorial on lengths is described in more detail in Silvia's answer). Saving the file as pdf, DOES enforce the plots to rasterize as expected, but then one runs into a whole bunch of maths fonts missing that is a whole other can of worms that needs to be addressed.
Either way, I don't think that giving presentations with Mathematica is failsafe so I can't say I'm entirely happy with either. One needs their own laptop or a laptop with CDF player installed and if you run into an (all too common) problem of someone forgetting a cable and you have to give the presentation using a portable format, neither of the above ways to export to pdf strikes me as intuitive/seamless (much as giving the actual presentation within Mathematica is really cool).