HOLLYWOOD — Never mind her trademark blonde locks: Kate Hudson enjoyed being a redhead most in “Alex & Emma.” Hudson changed hairdos frequently thanks to the writerly musings of the character played by co-star Luke Wilson, going red to play Elsa, a slatternly German au pair. “She was the most fun,” thesp said during Monday night’s after-bow bash at White Lotus.

Hudson admitted the variety of looks — not to mention role playing — was a big draw for her in choosing her latest romantic comedy. “How many times do you get to read female characters like that?” she asked.

Besides Hudson’s retinue — husband Chris Robinson, mom Goldie Hawn and brother Oliver — revelers included Warner’s Alan Horn, producer Elie Samaha, helmer Rob Reiner and dad Carl, pic’s David Paymer, plus Albert Brooks, Christopher Guest, Pete Sampras and wife Bridgette Wilson.