“What are the pros and cons of combining different types of messaging (such as wayfinding and advertising) in one display?”
Combining informational content with advertising content is how most of the Internet and advertising supported smartphone Apps work. It’s a great idea for public-facing interactive digital signage. Advertising works great as a large attract loop that plays when no one is using the screen. Once someone starts interacting, advertising can move to a smaller zone, allowing for the informational content to take over most of the display.
Large attract loops of advertising content on interactive kiosks aren’t as common as they should be. I find this is a missed opportunity, but it should be balanced. Some informational screens benefit from full screen messaging and a large call to action button encouraging interaction. The viewer needs to touch the screen to dismiss the attract loop and see the informational content.
In other cases, especially wayfinders, it’s a great idea to balance the information with advertising content. Showing the map at all times with a smaller advertising zone allows passive viewers to see what they want at a distance and doesn’t require anyone to touch the screen. This works well when viewers might be “shy” and don’t want to approach the screen.
Regardless of the approach you take, there’s nothing wrong with adding small zones for messaging or ad content on informational displays. Just find the right balance so everyone gets what they need easily. Think of your favorite websites, and take clues from how they balance ads with informational content. The best sites have learned that less is more.