I always go with my mother (80) my son and daughter (now 4 & 8) and my husband and sister. 6 persons, when my son is 2 years old, we went to Osaka and we go to China very often. But most of the overseas trip is 自由行, I don't prefer to follow the travel tour as it is too rush and no easy to bring old aged and young with so many time restriction.
personally think bankok would be the best choice , big shopping mall most came with children playground, the elderly can have tea or shopping at the same time,
and of couse famous thai massage is suitable for everybody