My son just finished a 16 month stint as an ADC. About half of his tour as the ADC was in garrison, the other half was in Iraq. Here are some of his observations, and my observations listening to him, his fellow ADCs, and his general.
1. Competition for the job is tough. In his division, every battalion had to submit the name of one lieutenant for the job. The general interviewed the candidates and chose who he wanted.
2. His general, had discussed with his contemporaries, whether the ADC's personality should be similar to the general's, or the opposite.
3. My son was part of the general's "official" and "unofficial" family. Where the general went, my son went. In garrison, if there was a meeting or social event, if it was appropriate for him to be there, my son was invited. When the general hosted an event, my son attended and assisted in anyway possible, including manning a grill or pouring drinks. In Iraq, my son went wherever the general went. He sat in on about 50% of the meetings, many of them with senior politicians and generals.
4. My son respected and admired his general. I have talked to several individuals who served as ADCs, who did not respect their general.
5. My son's duties included keeping track of the general at all time, managing his schedule, drafting correspondance, serving as an extra set of eyes when they visited units, and an extra set of ears when attending meetings.
6. Modern U.S. generals also have enlisted aides who do the typing, cleaning weapons, driving, etc.
7. Although my son was a very junior captain at the time, because he was the ADC, 90% of the field grade officers knew who he was. If he called and said "This is Captain Burnham, is Colonel Smith in?" He would be given instant access. If there was a question, then he would modify it to include his general's name.
8. The ADC had to be careful, when expressing himself, to ensure that he differentiated between whether he was talking for himself or in his capacity as the ADC. Tact is essential!