Louis van Amstel says he would have enjoyed the chance to work with Ann Romney. “Oh yes,” said the handsome dancer/choreographer best known for strutting his stuff on “Dancing With the Stars.” “Anybody can dance if they are willing to get out of their head and do it. … And we’ve had Mormons before, with Donnie and Marie [Osmond].” Alas, Romney, who’s known to be a big fan of the ABC show, was invited to be on but after some serious deliberation declined. Van Amstel (inset) is in town Saturday to promote his dance fitness DVDs called “LaBlast,” and to lead a master class at Avalon Dance & Fitness in Belmont. Among the many celebrity partners he’s worked with over his nine seasons on the show, we wondered who was the best. “Oh, definitely Kelly Osbourne,” he said. “She put in the time and really worked hard.” Not so successful was “Girls Next Door” star Kendra Wilkinson. “People think, ‘She’s a Playmate, she’ll be great,’ ” said van Amstel. “But she was a real tomboy. It just didn’t go well.” … The smooth-moving van Amstel isn’t the only “DWTS” alum in town this weekend. The AdMeTech Foundation is hosting a black-tie “Dance for a Cure of Prostate Cancer” bash Saturday, and “DWTS” dancers Mark Ballas, Jonathan Roberts, Anna Trebunskaya, and Nick Kosovich will shake it on the dance floor at the Westin Copley.