Traveler, I understand where you're coming from. I really enjoyed the Secret Files games, but they are . . . considerably quirkier than Lost Horizon. I think if you approach them with that mindset, you'll have a lot more fun with them.
Have you played the first one yet? Nina actually has several funny lines in that one, but I'm not sure that they're all intentional. It may be something in the translation. One of my favorites occurs when you have her grab several items from a shelf, and she says, "I'll take everything with me that is not on the trees by the time I count to three."
The original Nina's voice takes some getting used to, however. She sounds way too young for the role. Conversely, the original Max has a much nicer sounding voice than the Max from game 2, and the way he delivers certain lines can be very funny at times. Still, while they are fun games, I wouldn't expect them to live up to Lost Horizon as far as the story is concerned.
From what I remember reading, they actually hired a professional writer for Lost Horizon, and it showed. I think Lost Horizon is definitely their best game so far. I believe they have also hired professional writers for the upcoming Secret Files 3, so I have high hopes for that one as well.