Personally,
the camper van is one of my favourites, the sister sets of
the mini and
the beetle are also great. Theyre not on the scale of the Saturn V but few sets will be, especially at that price range.
It all kinda comes down to personal taste though, if you like buildings then stuff like the modular series look to be great builds, theres tower bridge and the architecture series too. The Star Wars stuff can be hugely impressive if you like Star Wars, theres 2 big Simpsons sets, the new Pirates of the Carribbean movie might be gooseberry fool but the Lego set to go with it is pretty great and the Ghostbusters Firehouse is an amazing build. The Ferris Wheel is a popular build and theres a range of "Winter" themed sets that they release every year, last years train was a popular one. The
Hard to Find section of the Lego shop is a good jumping in point, have a look and see what tickles your fancy.