With a baby on the way, parents-to-be Nick Lachey and Vanessa Minnillo decided to savor a night out at Tavern in Brentwood, Calif., over the weekend. The "super nice" pair joined another couple for dinner, and everyone listened as Minnillo talked about how wonderful her pregnancy has been. "She has this cute little belly," an onlooker tells PEOPLE.– Jennifer GarciaNEXT: Fergie and Josh Duhamel Party on St. Patrick's Day