One Note.
It's set up like books. You can make a notebook called, say, "Travel". Then each tab is like a "Chapter". I set up a tab for each trip. Within each tab, you can create pages. I set up a page for anything and everything:
- one page for a simple itinerary
- one page for details (all my times and confirmation numbers)
- one page to drop my flight confirmation
- one page for each accommodation confirmation
- one page for my packing list
- maybe a page for the map of the layover terminal and where the lounges are
- maybe a page for luggage limits on THAT trip for THAT airline...
- a page for my To Do and To Buy lists
- a page to track weather trends.
You can type, draw, paste pictures, build tables, or create a page with lots of different content areas (like a newsprint spread). Post links, format your text with color, boldface, different fonts - whatever. The app makes it very easy to highlight what you need.
You can "print to One Note" from your email. So all those confirmations can just be printed to a blank page in your notebook, then renamed however you like.
One Note can be accessed from multiple devices, and you can share specific chapters with other people. I usually build most of my trips using my laptop, but while travelling, I only have a phone. Slightly different functionality on a phone/tablet, but it still works really well.
AND... if you make a point of opening every page each day (for that trip), an offline version will be available for a few days. I've been known to screenshot driving maps, paste the screenshots in One Note, open that One Note page while on my hotel WiFi in the morning, then head out into the wild with confidence I had good non-paper maps available. Also works for the page on which you keep confirmation numbers.
I use my One Note as a planning tool, so i have everything where I need it from the moment I start researching a trip. Another GREAT part is you can search across multiple open notebooks, so your past research is just a click away.
I have a dozen or more notebooks (travel, household projects, camera/photo, education, etc.) and probably thousands of pages by now (10+ years using). This year, I decided to pay the annual fee to expand my memory - the free option offered by Microsoft was plenty for many years of dropping pictures, pasting whole webpages, and lots of digital "printouts".