So Saturday night, the AT&T PAC threw its cumulative wingding-gala, the final fundraising frolic before Sunday’s open house, when the whole Arts District welcomed the two freshman facilities by getting all free and easy with a day’s worth of open-admission museums and concerts. Think of it as kind of a cultural Rush Week.

So anyway, Saturday night, the Winspear put a 50-piece orchestra onstage (give or take a few oboes) and had them back up an eight-member chorus line and a trio of Broadway belters — Kristin Chenoweth (left), George Hearn and Patti Lupone — plus one twirly-footed. Tony-winning kid, Kiril Kulish from Billy Ellliot. Then we all had drinks and dinner out in the middle of Sammons Park, where a long row of tents had been set up (it was a beautiful night for it, although it got a bit breezy and chilly for the women in low-cut, backless gowns without a wrap) before we shimmied over to the Wyly, which had done its quick-change thing from the night before, when it had been all professional-proscenium for the repeats of its lead-off theater gala from Wednesday. Poof, the theater balconies and stage were gone, and the Wyly was a nightclub. If you’d been there only 24 hours previous, it was impressive. Where’d everything go? All that was left was three walls of glass.

So the evening rundown went like this:

Kulish – spin, spin, spin, spin. Doesn’t he get dizzy?

Chenoweth — the Oklahoma kewpie doll with the freak-of-nature soprano voice beguiled the crowd by showing up in a Longhorn jersey (she’d lost a bet on some afternoon game or other) and probably won over quite a few trophy wives by singing their anthem (and what has become Chenoweth’s own incredible signature showcase), “Glitter and Be Gay” from Candide.

Hearn — no audience chitchat, he just impressed us all with his powerful baritone, particularly his ring-the-rafters version of “The Impossible Dream.” Too bad he didn’t sing anything from Sweeney Todd, though, because it’s his version that’s a towering masterpiece (sorry, Johnny Depp fans).

And then Lupone came onboard and blew out the back wall of the place with her greatest hits: Evita, Anything Goes, Gypsy, Pal Joey. Too bad she didn’t sing anything from Sweeney Todd, too. I never got to see her Mrs. Lovett. The best replacement for Ethel Merman Broadway’s ever found.

Everyone was miked, natch, but the sound was much better than the reported snafu during Thursday’s opera gala, when nobody could understand the architect, Norman Foster. Only one glitch (we got a high hum after Chenoweth departed) and the mix was a little muddy during some of the chorus numbers.

Over at the Wyly, the funk band sound was merrily deafening while we all danced and sipped, but that didn’t stop Zach Quinto (the young Spock) from graciously chatting with the many women who traipsed up to talk to him and take his picture. Or so my wife tells me. She made a point of complimenting him on it.