No strippers here! Jessica Simpson and fiance Eric Johnson bucked tradition and said goodbye to their single days with a joint, co-ed bachelor-bachelorette bash devoid of any X-rated entertainment-but still plenty entertaining!

Rather than split into two groups of girls and guys, the bride and groom-to-be gathered their friends and family together in one big group for a night on the town in West Hollywood on Sunday, June 8. Joined by their loved ones, the couple hit up Eveleigh restaurant on Sunset Boulevard, where they dined on appetizers and small plates and sipped some of the hotspot's signature cocktails.

An onlooker tells Us Weekly that Simpson, 33, "couldn't have looked happier" as she sat next to Johnson, 34, with whom she has two kids, daughter Maxwell, 2, and son Ace, 12 months. "They kept raising their glasses," one source recalls. "They were having a great time. Jessica looked absolutely amazing-and tiny."

The eyewitness adds that the alcohol was flowing. "There was a lot of vodka...and they had champagne for toasts, too," the onlooker tells Us, noting that Weight Watchers spokesperson Simpson didn't seem to eat that much, even though "they had plenty of food" on the table. "There was a lot of fish, like the ceviche and squid dishes," the source says.

"Jessica looked very cute sitting next to Eric," the witness tells Us. "He had his arm around her shoulders, and I saw them kiss."

After the meal, the group continued on to Warwick nightclub, where they were photographed leaving in the wee hours of the morning. Simpson sizzled in a sexy little black dress with a cleavage-baring V-shaped sheer panel cut halfway to her navel.

The fashion mogul and her former NFL pro beau have been engaged since 2010. As Us Weekly exclusively reported in May, they're set to tie the knot in a wedding over the July 4 holiday weekend.

Source: US Weekly