How do you currently organize/manage your trips?

Curious how everyone handles trip planning. Do you use spreadsheets, Google Docs, a dedicated app, or just wing it?

A few things I've always found painful:

• Keeping track of booking confirmation emails across flights, hotels, and activities

• Splitting costs with friends after the trip

• Finding good restaurants and actually making reservations

• Having one place where everyone on the trip can see the full plan

What's your biggest headache when planning group travel? Would love to hear what's working (and what's not) for people.