You can check out the current state of my project at http://www.glueckslaterne.de and get a rough impression of the context the logo would appear in. However it's all in the making and I'd be happy to change the whole style to suit the new logo.
Thanks everyone for your contributions! After the first designs coming in my ideas are getting clearer. Here are a few additional thoughts:
1. The design should be much simpler than most of the contributions so far. Friendly but clear forms and not to many colors. Green or blue and a spark of orange/yellow to represent the light is enough. Simplicity and minimalism are also part of the project's philosophy. It's about concentrating on the essential things and finding happiness there.
2. If you're going for two parts with one part representing happiness and the other part the lantern/light the lantern should be the main part. However I'd prefer a solution in which the lantern is the only (vaguely) recognizable form and the aspects of hope and happiness are represented in a more abstract way. It could be something akin to a smile but not an actual face. Just rounder forms and warmly colored light inside or eminating from the lantern could be enough.
3. I'd love to see more typography based designs. Maybe you can play with the letter G and try to turn it into a lantern. I also feel that a cursive font could be suitable to convey the aspect of happiness in a more abstract way.
So to summarize the logo should definitely...
1. be very simple.
2. look like a lantern (not necessarily at first sight but at least if you know it's a lantern it should become obvious).
3. convey happiness using warm colors, round forms etc., maybe adding a smile in a subtle not too obvious way.