Everyone else has covered the major points. I will say one thing though. This may be more debatable, but I personally don't like it when signs have the flight path of the disc shown. Some holes may have a certain flight path most people would use, but some might like a different approach/different shot. When the sign doesn't show a flight path, I think that encourages people to be more creative. Someone might have one idea, while someone else has a completely different idea on the hole. This way no one enters the hole with a preconceived perception of how they're supposed to throw. Not a huge deal, but that's my opinion.
Edit: I don't mind having the fairway defined from the rough on signs. Just the actual flight path line.
I respectfully disagree. Tee signs are of most use to first timers and vistors. A "typical" line indicates where you'll find the basket. As someone else said, when visiting/playing for first time,
I just want to know where the pin I'm supposed to throw at is. A simple line w/ distance does that effectively and efficiently. Anyone who wants to take a different route can be as creative as they wish.
Sure, color signs are nice when they're new, but how long before they get:
1) drawn on (Aces, vulgarity, whatever)?
2) damaged, destroyed, stolen
3) outdated - hole changes, pin/tee gets moved
Custom signs are harder to replace.
Simple 4x4 posts are cheaper and easier to make initially, and cheaper and easier to replace as required down the road.
The only real reason I see a need for actual signs are to show multiple pins and which position it's in at the time.