When I planned a trip to Spain, I use the Frommers 3 days guide in Madrid to plan activities.

http://www.frommers.com/destinations/madrid/0056020791.html

I then used Google Maps and created a custom map with all the suggested sites, activities, and eateries. I was also able to share it with my friends and collaborate over it.

I think this is a great opportunity for Google to streamline all this and make another great product.