The Phantom of the Opera includes a few sequences designed to make you "ooh" and "aah" just from all the pretty effects they exhibit. The regenerating theater at the beginning, boat scene, bridge and, of course, the chandelier all fall under this. This and other examples of style over substance are a big reason the show has a lot of haters.
The musical version of Sunset Boulevard exhibits this in several of its effects, including one where the stagehands actually built a ''split screen", with Norma Desmond's famous staircase on the top and a party scene on the bottom. This eventually proved to be the original production's downfall, as it was too expensive to run with anything less than capacity audiences.
After intermission, the musical version of The Producers brings out an identical set to the office, except painted completely white (even the windows and desks) for little more than a cheap gag and to show us how much money they spent.
Similarly 42nd Street, also meant to evoke the Follies, as well as the movie musicals of Busby Berkley. Where did they get all those costumes in Depression-era New York anyway, especially since it appeared to only be the first rehearsal?
Sunday In The Park With George has both a straight example and a subversion. Act I involves the actors and a few flats, recreating a famous painting almost perfectly onstage. Later, in Act II, they put on an impressive laser light show, and then make a deal out of it being all flash and no substance.
Speaking of Sunday, the recent revival recreated both of the above effects with a set made entirely of giant computer screens.
Theatre's dual champs of Scenery Porn could be Cirque du Soleil's "O" and KA, in Las Vegas. The theatres were specifically built for them, which is standard for all non-touring Cirque troupes, but these take it to a whole new level. (Of course, other Cirque shows also boast amazing set design — turntables, ascending/descending stage sections, projections, etc. — and mindblowing acrobatics.)
Lampshaded in Spamalot, with references to King Arthur and Patsy being lost in "A Very Expensive Forest", complete with flashing dollar signs on the obviously-cardboard trees.
The London production of Voyage, the first in Tom Stoppard's exhausting trilogy of plays about Russian thinkers The Coast of Utopia, utilized a backdrop of photorealistic video imagery projected on a massive white semi-circular screen that curved around the stage. During scene changes, the video would pan and scan to the next frame - for example, from the yard to the manor. Overall, the effect was pretty stunning.
Tanz der Vampire has so much Scenery Porn. There are several gorgeous sets, but if the scene of Sarah coming into Krolock's castle for the first time doesn't have your chin in your lap, then nothing ever will. The second you realize that the chorus is being sung by the portraits — which until that moment anyone would have sworn were actual paintings - that is a Crowning Moment Of Awesome.
In the Heights has an amazing set. The set designer had an eye for detail. There are so many little things that really make it amazing. During the actual show there are people in the apartments doing things.
American Idiot's set is deceptively simple — they have set pieces that move, tip over, and make amazing use of projections (particularly in "Boulevard of Broken Dreams" and "Wake Me Up When September Ends").
Both the Broadway and London productions of Jerusalem.
The 2013 Charlie and the Chocolate Factory stage musical is, aptly, packed with fairytale eye candy: An ever-moonlit junkyard, colorful mini-sets within a huge TV that achingly contrast with the gray, ramshackle Bucket residence...and that's just Act One. Act Two, set within the titular factory's Amazing Technicolor World, has projections that turn the stage into ever-twisting hallways to dash through on the way to giant sets for such locales as the Chocolate Room and the Department of the Future (where Mike Teavee gets his comeuppance). The climactic scene turns the stage into a starlit sky for the Great Glass Elevator to literally ascend into.