A round-up of not-to-miss, upcoming events: Get 'em while they're hot!

September 23:

San Francisco Botanical Garden Mayor Gavin Newsom receives the Green Champion Award for his leadership in pioneering green initiatives in San Francisco at the annual Garden Feast Luncheon. The event features a reception and silent auction, seated lunch and keynote speech by biologist-environmentalist Nell Newman. 11 a.m. Wed., Sept. 23. Strybing Arboretum, Ninth Avenue at Lincoln Way, Golden Gate Park, San Francisco. Tickets: $175-$1,000 (individual); $1,750-$10,000 (tables of 10).  (415) 661-1316, ext. 304.

September 24:

SFMOMA The 2nd SF20 show and sale (Sept. 24-27) features 20th-century decorative and fine arts from local and national dealers, as well as a lecture series by local designers. A portion of proceeds from the opening-night preview party on Thursday (Sept. 24) benefits the SF Museum of Modern Art. Honorary chairwoman: Elaine McKeon; Event co-chairs: Katie Schwab, Allison Speer and Stanlee Gatti; Designer Circle chair: Douglas Durkin; Connoisseur co-chairs: Heidi and Caley Castelein. Herbst Pavilion, Fort Mason Center, San Francisco. Preview-party tickets: $150; $1,000 (early entry, 6:30 p.m.); $2,500 (early entry, 6:30 p.m.); $5,000 (early entry, 6 p.m.). General admission tickets (Fri.-Sun.): $15.

September 25:

California Academy of Sciences The 2nd Big Bang Gala celebrates the Academy’s successful first year of evolution. The evening (which benefits museum programs) features self-guided museum meanderings, fine food, dancing under the stars and a concert by Chris Isaak. Honorary co-chairs: Mayor Gavin Newsom and Jennifer Siebel Newsom; Barbro and Bernard Osher. Event co-chairs: Janet McKinley and Susan Oberndorf. Fri., Sept. 25. 7 p.m.-1 a.m.  Music Concourse, Golden Gate Park, San Francisco. Tickets: $125 (9 p.m. entrance includes light noshing, dance party, concert); $400 (7 p.m. entrance includes buffet dining, dance party, concert). (415) 379-5420.

October 2:

Golden Gate National Parks ConservancyTrails Forever 2009, a rustic-gant gala, comes to attention in Fort Point with hors d’oeuvres and history, a march along the waterfront to a dinner and live auction of one-of-a-kind “Only in the Parks” exploration packages, followed by a fireside victory celebration set to the tunes of Poor Man’s Whiskey. The evening raises funds for the Conservancy’s conservation efforts and trail system infrastructure. Event co-chairs: Nancy Bechtle and Jessica Galloway. 6:30 p.m. Oct. 2. Fort Point National Historic Site, the Presidio, San Francisco. Tickets: $400; $1,500 (for two); $4,000 (for four); $6,000 (for six); $10,000-$50,000 (sponsor tables of 10). (415) 561-3029.

October 17:

Bay Area Arthritis AuxiliaryLily Samii is the featured designer at this luncheon-fashion show which features pieces from the Resort and Spring line and pays homage to Samii’s 20th anniversary. Honorary co-chairs: Layne Gray and Joanne Horning. Event co-chairs: Gail DeMartini and Jane Inch. A reception and silent auction begins at 10:30 a.m. Lunch follows at noon. Thurs., Oct. 15. St. Francis Hotel, 335 Powell St., San Francisco. Tickets: $150; $300, $500 and $1,000 (individual patron’s tickets); $1,500-$10,000 (sponsor tables of 10). (415) 356-1230.