Take then here... (Hutong in TST)
If you want a good Chinese with very good service, head to one of the bigger hotels such as Excelsior, Mandarin, Shangrila and similar.
If they're responsive to tourist guides (as in get a kick out of visiting places cited in them), and if they don't mind somewhat rushed, diner like places, show them these articles, then take them to Tim Ho Wan.
36 Hours in Hong Kong - The New York Times
Tim Ho Wan restaurant, Hong Kong: the hottest meal ticket in town - Telegraph
But make sure you go off peak so there are no lines and it's less crowded. Otherwise the elderly folk I know will get drained by the whole experience. I've usually just taken my overseas visitors to the one in Central Station, for convenience and because the wait tends to be shorter. The goal is to give them an experience they can relate to from international publications, restaurant with a nice back story (ex 3 star Four Season's chef), and tell their friends back home accordingly, regardless of whether this is the best or cheapest or tastiest dim sum they can eat here.
Cheung chau or Tai O. Good place for them to get some feeling of traditional Hong Kong stuff. Meanwhile, they can sit somewhere for eat n drink if they feel tired.
@dddc - Here's a recent review of the Fook Lam Moon.
Hong Kong’s top restaurants: Fook Lam Moon in Wan Chai – upscale home-style Cantonese, and doggy bags for leftovers | South China Morning Post
- Western market top floor for dim sum, nice food with nice service
- Cheung Chau for "typical" chinese village
- Peak tram
- Stanley for souvenir crap
- 10 000 bouddhas if they dont mind the stairs.
One of my favorite "bang for buck" walks in which you get to see some spectacular scenery is taking a taxi to Park View and then at the very end of the road you can keep walking (becomes pedestrian only road). Sometime after is a turn off to the Tai Tam Family Walk. It's all downhill and very pleasant with some beautiful views and outlooks of the valley. When you get to the reservoir there are plenty of options to continue and walk out. Sometimes when it's too hot or I haven't been feeling well, we've really enjoyed this as a way to get out in nature but without having to exert ourselves.
If you want a slightly more challenging walk in the area, but still relatively easy, is Violet Hill. Also very stunning views. Again, lots of options at the bottom junction for how to get out (catch water walk towards Stanley, short 10-15 min. walk out to Repulse Bay, or walk further towards the reservoirs). Don't, however, consider the Twins as a continuation if they are not very fit and into hiking.
Tin Ho Wan is not really worth it or anything special in my opinion. Dim Dim Sum is better. Also, Tim's Kitchen does very good dim sum in a little nicer/cleaner/quieter atmosphere, but they also serve shark's fin, so I personally have boycotted them.
Update: We did the Peak which I think was just OK for them, as well as Nan Lin Gardens (with the nunnery) which they really liked, and also the 102/F of the Ritz for an evening drink and to watch the sunset which they really liked as well. Star ferry was great too. Food wise they actually liked Lin Heung and Tim Ho Wan better than the upscale places. For anyone else planning a similar trip, would suggest staying around the city areas (i.e. non outlying islands) where it's easy to insert rest stops and the bathrooms are cleaner. We didn't manage to do the Lantau Buddha since the commute has apparently become horrifically long since the cable cars have been taken off duty.
Thanks everyone for the earlier suggestions.