While galleries flower around our region with the regularity, joy, and oomph of real-world blossoms, a fresh museum's arrival tends to be rather rarer. This furthers the often misplaced idea that a museum can be a tad ponderous, and weighty, and permanent. But the lightness of LA's newest entry into the world of museumdom belies such notions, even as it fills one of our city's most stately structures, the Millard Sheets-designed Scottish Rite Masonic Temple at 4357 Wilshire Boulevard. It's the Marciano Art Foundation, from Guess co-founders (and brothers) Paul and Maurice Marciano, and, with its May 25 debut, it will now draw art lovers from the area, and far beyond, to a building brimming with contemporary wonders. Wonders, we'll add, that telegraph wit, complexity, and a layered look at modern life. What's the cost to visit? It's free, but a reservation well in advance is a must.