I know what you mean. Some people just cannot get that exited about anything. What a sad life they must lead.
I take people on a similar trip most weekends, give them my best tourguide speech of the south of england, entertain them with steep turns, give them their first go at flying a plane themselves and just not impressed.
Others wear giddy smiles from take off to touch down. The best ones are the ones that just want you to make it go tippy all of the time (about 1 in 100 trips on average).
Yet stick me on a pole 2000 feet above the airfield and I'd never get bored looking out. Every time you go up you see somthing you've never seen before.
Anyway if they all wanted to do it imagine how busy it would be up there.
The most gaulling thing is you paid for it. I'd have at least got the cost share and lunch out of the miserable git.