Paul Allen and Denise Rich both hosted exclusive bashes on their yachts in Cannes Monday. But Alec Baldwin didn’t make it to his own movie’s after-party on Rich’s “Lady Joy” so he could stay by the side of his pregnant wife Hilaria Thomas. A private dinner followed by a late-night blow-out was in celebration of Baldwin and James Toback’s “Seduced and Abandoned,” and guests went through 100 cases of Perrier-Jouët Champagne, spies said. But Baldwin was MIA. Spies said he and Thomas’ flight to France was delayed and they’d had to race from the airport to the red carpet for the film’s debut. After that mad dash, pregnant Thomas wasn’t up for partying and Baldwin dutifully stayed with her. Aboard another yacht, Allen’s “Tatoosh,” the billionaire hosted his annual Cannes party for guests including Goldie Hawn, Adrien Brody and Michael Douglas. The Microsoft mogul provided entertainment by jamming with his band, spies said.