A massive, sometimes brilliant staging of one of the greatest musicals ever written, and a pleasant, slightly under-paced staging of a frothy little sherbet of a play. These shows share two things in common: both are musicals, and both feature stunningly good performances by their exceptionally good leading ladies.

Directed by Craig Miller, “Thoroughly Modern Millie” is the stage adaptation of the 1967 Julie Andrews film, substantially reworked for the stage in 2000, by Richard Scanlan and Jeanine Tesori. It tells the story of a naïve newcomer to New York City in 1922, a “modern” woman with a bold scheme to get a job and marry her boss. Her plans are thrown into disarray when she finds herself falling for a penniless paperclip salesman, and further complicated by a secret white slavery ring that appears to be operating out of the hotel for unemployed actresses at which Millie is staying.

Whether or not the use of white actors to play outrageous Asian stereotypes is racist or just unwise and unfunny, I will leave for others to debate.

Essentially, it’s just a silly play, nice enough but with few memorable tunes, and a lightweight cotton candy superficiality that is meant to entertain, but not really say anything. But there is a reason to see this production. As Millie, Rebbekah Pearson is sensational. She’s got the right kind of voice for this style of Broadway belting, and also the acting chops to pull off the complicated blur of emotions and impulses that is Millie. Many of her co-leads are strong, with special emphasis on Evan Atwood, who is an absolute stitch as Millie’s off-the-wall bachelor boss. But it’s Pearson, a newcomer to the 6th Street Playhouse, who gives the best reason to catch “Thoroughly Modern Mille,” lightweight as it is.

The show aside, it’s star is one to be watching in the future.

“South Pacific,” on the other hand, is amongst the least lightweight musicals ever created, though it is filled with light, charming moments and some hummably happy tunes. Originally staged in 1949, the musical was adapted from James Michener’s World War II novel, the Pulitzer-winning “Tales of the South Pacific,” and follows the motley characters who live on and around a U.S. Navy base on a small Polynesian island.

Even after all these years, the writing in “South Pacific” still seems crisp and clean, gradually revealing details in a cleverly structured series of scenes that are less about war and the military than they are about the complexities of human interaction.

And the songs, from “Some Enchanted Evening” and “Younger Than Springtime” to “Happy Talk” and “I’m Gonna Wash That Man Right out of My Hair,” are some of the best ever composed for the stage.

And once again, amidst a cast of fine actors and colorful characters, it is the stellar performance of its female lead that makes this show a must-see. Taylor Chalker, as the optimistic but emotionally conflicted nurse Ensign Nellie Forbush, who pushes an already excellent show, very well directed by Linda Dunn, way up to the next level.

Which is saying something.

The thing about the Mountain Play is, it’s not easy to be an actor up there, playing to a four-thousand seat house. But Chalker has the voice to sell everything from the softest heartbreak to the most exuberant self-confidence, and strong supporting performances, by a large cast, are cream on the pudding - especially Randy Nazarian as the comically scheming Luther Billis, and Peter Vilin as the French landowner Emil.

Director Dunn has filled the show with visual razzle-dazzle and authentic detail, packing the frame of the stage with working jeeps and trucks, a sprawling French Villa, a lookout tower with a constant sentry posted up at the top, and even a pair of planes which buzz the open air amphitheater at a crucial moment in the show.

“South Pacific,” without question, ranks as one of the best Mountain Plays in recent memory.