Taking the boys camping next month, need gear advice

Planning our first real camping trip with the kids (ages 4 and 8) at a state park about 90 mins away. We've done backyard camping but this is the real deal. Already have a decent tent but I'm torn between buying a new sleeping bag setup vs renting. Also wondering if I should get one of those camping stoves or just stick to the campfire. Budget is like $300-400 to start. Anyone done this with young kids? What did you wish you had brought?