Anything you do in Iceland in July will be epic! Blue Lagoon is nice, although I wouldn’t do it a second time. The Golden Circle is a nice day trip. The black sand beach at Vik is a good stop. Jokulsarlon Ice Lagoon is a good distance but memorable. Seltun is otherworldly. In Hafnarjordur, there is an “elf tour” if they are into Harry Potterish stuff.