My kids are 6 1/2 years apart with the younger being 4. Finding games to play together has been a challenge, but not impossible. Cranium games are usually adaptable to various age groups. Games of luck such as Don't spill the beans, Operation, Buckaroo or Tumbling monkeys are easy to play with various ages. Bingo is also good for DS4 for numbers and letters while DD calls the numbers for the rest of the family.
I usually buy board games when they are on clearance and we have accumulated quite a few. Having a variety of games is helpful to prevent boredom.
Jen