Jeff Hiller is Gerry in Studio Theatre’s one-man show “Bright Colors and Bold Patterns.” (Russ Rowland)

Given the title, one might hope that the solo show “Bright Colors and Bold Patterns” would be more tonally variegated. But the same expressive timbre too often prevails in this admittedly funny dramatic rant, written by Drew Droege, directed by Michael Urie and staged as part of Studio Theatre’s “Showroom” series.

Performed by Jeff Hiller with deliberate tinsel-bright energy and emphasis, the 90-minute monologue is set in Palm Springs on the evening before a gay couple’s wedding. When the loquacious, hyper-animated guest Gerry arrives, he’s keyed up over personal troubles and the wedding’s conservative dress code, which prohibits bright colors and bold patterns. As he hangs out poolside with his ex and his ex’s much-younger new boyfriend (both invisible to us), Gerry spouts off archly on such topics as age, same-sex marriage, gay culture, Olympia Dukakis, the Waze traffic app and the irritating moniker of the pop band the 1975 (“I’ve never been so mad at an article!” he proclaims of the “the”).

A skinny loner in a flowered shirt and shorts, often nursing a margarita decked out with two parasols and a tiny flamingo, Hiller’s Gerry is an attention-grabber who turns hyperbolic gestures and facial expressions into high art. (His goal for the evening is “fun, fun, fun!” he declares, miming a game of patty cake.) Gerry’s dismissive zingers — sharpened by his own anxiety and loneliness — are consistently hilarious.

The wedding party isn’t immune from the snark. (“He’s just . . . there. Ya know? He’s like an ottoman,” Gerry quips of one of the bridegrooms.) Nor is the decor, although from our perspective the backyard beach-party aesthetic (cluttered bar, tiny Chinese lanterns, etc.) designed by Dara Wishingrad is pitch perfect.

Because the jests, smart-alecky opinions and name-dropping are nearly unflagging, there’s an intense poignancy to the moments of seriousness: a recollection of a romantic betrayal, a hesitantly voiced worry that, for gay couples, marriage can be a step toward drab conformism. Such confessions are truly moving.

But these contrapuntal beats are too infrequent, and the director, Urie, hasn’t worked enough nuance into the more antic sections. As a result, “Bright Colors and Bold Patterns” too often feels like a single overstretched idea.

“Would somebody please show me on the rainbow where I can find khaki?” Gerry complains at one point, speaking of what he sees as the staid mainstreaming of gay relationships. As a connoisseur of rainbows, he would surely prefer to be in a show with more emotional chromatics.

Bright Colors and Bold Patterns, by Drew Droege. Directed by Michael Urie. 90 minutes. $45-$55. Through July 28 at Studio Theatre, 1501 14th St. NW. 202-332-3300. studiotheatre.org.