Ask HN: Good travel planning app?

I'm looking for an app to help me plan a trip around the U.S. and Europe in the next few months. I'd like it to be easy for me to paste in ideas for attractions / things to do / places to stay, and to see how changing plans changes the price. And, it would be nice if it were easily shareable and collaboratively editable.

I was just going to do a Google Spreadsheet, but that seems so dry.