Nice comedic work from Sam Rockwell and Allison Janney buoys this pleasant but routine coming-of-age drama by Nat Faxon and Jim Rash. The hero (Liam James) and his divorced mom (Toni Collette) arrive in a coastal town for a summer vacation with her jerky new boyfriend (Steve Carell); to get away from him, the kid gets a job at a dilapidated water park, where he acquires a free-spirited mentor (Rockwell). There’s the requisite cute girl next door (AnnaSophia Robb) and adolescent struggle with adult perfidy, as the kid catches mom’s sweetheart cheating with an old girlfriend (Amanda Peet). Faxon and Rash, busy actors who kick in here as eccentric employees at the park, won screenwriting Oscars for Alexander Payne’s The Descendants, and their directing debut shares some of that movie’s strengths and weaknesses, with smart, funny dialogue undercut by stock situations. With Rob Corddry and Maya Rudolph.