Would it be possible to compare the user experience in both the airbus 380 and the Boeing 787 in one (return) trip? I don't mind making connecting flights inbetween in other models.
As far as I'm aware, at time of writing the only airlines that currently operate both the 787 and the A380 are British Airways and China Southern Airlines, although Etihad will be joining this rather exclusive club by the end of the year, and Korean Air, Singapore Airlines and Virgin Atlantic have all placed firm orders for both.
That said, the obvious problem with flying a A380 one way and a B787 the other is that the airline has to fly both aircraft both ways as well. BA's summer 2014 schedule has no overlapping routes for the two, and (as far as I can tell) neither does CZ; neither is there much in the way of overlap between the route networks of these two.
However, if you're willing to stump up for two one-ways on different carriers, there are a number of options. The first I could find is Singapore-Tokyo, where you can fly one way on a Singapore Airlines A380, and return with an ANA or JAL B787. And since ANA and SQ are both in Star Alliance, you might even be able to swing a return fare combining the two at a not-insane price.
If you're willing to travel a bit, your choices open up even more; you can try to spot nearby city pairs on this map of A380 routes and this list of B787 routes. For example, you could take a Lufthansa A380 from Frankfurt to New York-JFK, then fly back to Warsaw on LOT's 787 service.