Not to typecast, but since Rock in Rio Lisbon is a music festival in Europe, we were hoping for loads of good dance music. Like the kind we're generally not hearing in the clubs up and down the Strip. And we were mostly rewarded—though there was literally no escaping Steve Aoki. More on that in a bit.

An introduction to the musical programming structure: Rock in Rio, be it in Lisbon, Madrid, Rio de Janeiro and, come May 2015, Las Vegas, focuses on a musical genre on each of its days. Yesterday the focus was what organizers call "hard rock," with Linkin Park and Queens of the Stone Age co-headlining. Today, it's vaguely alternative with Arcade Fire topping the main-stage bill, followed by Lorde and Ed Sheeran.

These main stage lineups are complemented by an indie stage on the opposite end of the festival grounds—a hilly, grassy expanse called Parque da Bela Vista; a fake cityscape called "Rock Street" with an up-and-comer stage booked with talent indicative of the countries themed into the facade; and an electronic dance music stage that's mostly open late at night, and shaped like six-legged spider.

Over the course of the four days (and a pre-weekend festival day on May 25), the electronic stage boasts a wide variety of DJs and live acts, most of them veering from the dance-music status quo. That's partly because the stage's budget is small, and partly because the man booking it, Miguel Marangas, while being the sort of guy that never says never, would seem loathe to book a "big room" DJ—especially in Lisbon, which is accustomed to experiencing acclaimed and respected DJs. Judging by how enthusiastically he rattles off certain names, he likely prefers house music that's deeper, more soulful, maybe also has roots in disco.

Which, should Marangas be officially selected as booker for 2015, bodes well for those of us who hope that the Vegas edition of Rock in Rio largely dodges commercial EDM. Right now, Marangas—and festival head Roberto Medina, for that matter—has a bigger problem than bombastic, overpriced DJs: the Clark County Commission, which must still approve the hours of operation of Rock in Rio USA. Once that's settled, they can start strategizing the DJ lineup, and given the Las Vegas nightlife landscape and how Medina and crew like to do things their way, won't that be interesting.

Back in Lisbon, plenty of that deeper, more soulful, disco-kissed house was on offer, especially from North America and toward the end of last night. While Aoki enthralled a throng that was arguably bigger than the one Linkin Park drew, Bay Area house/techno favorite Claude von Stroke had an initially small crowd shuffling along to his subterranean, late-night grooves. When the main stage crowd soon had only the electronic stage left to entertain them, Von Stroke found himself facing a large audience, and brought the energy level up with slightly faster tempos. I wouldn't call it a raging party, but the vibe was nonetheless invigorating.

This set up Canadian producer/DJ Tiga, the de facto headliner at the spider. He wasted no time, quickly delving into house crowd-pleasers like Green Velvet's "Bigger Than Prince" (the vocal sample: "Walk around like you're bigger than Prince") and his own "Let's Go Dancing," which he made with Audion—aka Matthew Dear—and is most recognizable by its "Let's go dancing/I wanna go dancing with you/all night dancing" vocal hook. This prompts a little more non-shuffling dancing, though by now I'm learning the Portuguese get down with subtlety. They outlast me, frankly, but for as long as I can hear Tiga's set, I don't detect a false note or bum track.

Hours earlier, New York's Hercules and Love Affair performed a live set, and while the nu-disco/electro tracks didn't disappoint, it felt like there was something missing from the performers—principals Andy Butler and Mark Pistel working the hardware in the back, singers Gustaph and Rouge Mary up front—and one of those things was engagement. Some perspective: This is a newer lineup, and the act hasn't played very many live sets together. The music provoked escape, just not enough to drown out the bombast behind us.

Speaking of which: Who knew Steve Aoki—who as a special electronic main-stage inclusion was not booked by Marangas—was such a megastar outside of America? Apparently I'm the last to know these things. He not only earned a deafening roar when he appeared at the end of the Linkin Park set (during "A Light That Never Comes," which he remixed), but he actually appeared to draw more people than the multi-platinum band with whom he briefly appeared. His audience was unfathomably enormous and ready for a party. By the way: It appears Europeans also stare at the DJ and jump up and down after the drops and wave foam glowsticks in the air like idiots. So much for Vegas ruining dance music.

Aoki's cacophonous electro-house set came with everything you expected: The pronounced drops, the nails-on-chalk acid-line melodies, the cake tossed at the crowd, the inflatable raft he had a female onlooker ride atop her fellow audience members, the selfie in front of the crowd and the numerous leaps from the DJ booth. And then there was the unexpected—namely, the remix of "Circle of Life," from The Lion King. And the sight of each and every TV screen on festival grounds surrounded by non-fans who were nonetheless compelled to watch this tour de force of goofballery—a discernible yin to the electronic stage's yang.

Tonight, that stage will feature, among others, DFA producers Benoit & Sergio and experimental/minimal DJ Frivolous. For tomorrow's finale, notable names include Brazil's Renato Ratier and England's John Digweed, and a live closing set from a reunited Underground Sound of Lisbon (aka Portuguese producers Rui da Silva and DJ Vibe), a fitting close to the country's biggest musical gathering.