The Summer Place by Jennifer Weiner

 This is a good book for a day at the beach. Sarah and Sam are (adult) twins. Veronica (Ronnie) owns a beautiful house on Cape Cod that she loves and that she hoped would be the gathering place for her family. But that's not how things worked out. Her daughter Sarah is married to Eli and living in NYC with Eli's daughter, Ruby, and her and Eli's 2 young sons. Ronnie's son Sam lives in California with his stepson Connor. And no one makes it back to Cape Cod much. Then Ruby announces that she's getting married to her boyfriend Gabe and the wedding will be at Ronnie's on Cape Cod. And so begins one crazy adventure, where several family members are trying to decide whether they've chosen the right significant other and Ronnie herself has several big secrets that she thinks it's time to share with her kids. It's an enjoyable romp with a colorful clan.