5 days tour Beijing

Hi, I'm from Korea and I'm planning to visit Beijing on this coming August for a 5d4n trip. Members joining will be 2 pairs of young couple and a pair of older age couple. Would be very much appreciated if you could assist in planning us a 5day tour itinerary along with a must try/buy foods/goods in each spot.
Considering of some older ages members, do you think it is more appropriate for us to sign up an agency tour guide service or can we just do our own touring with public transport available in BJ?