Dropbox does store files locally.... Simply mark the file for offline reading.(older editions called in "favorites) .... I do this during prep.  When no service,  simply go to dropbox  and click on your file as usual.    If you want you can go to "offline files"  in the menu to see all of your files marked "offline" and check sync history. 

I also use bookmarks with Adobe reader... I have it as my Dropbox default pdf reader as opposed to dropbox's reader which has limited features. 

With evernote I have all my folders  nested in a master folder and the master folder set for offline reading.   So everything  saved in my Evernote master folder is automatically is stored locally as well. 

 right  now dropbox is requiring I need connection for the program.... . with evernote, you don't...... gotta recheck

ok.. rechecked my Dropbox by putting phone on airplane mode.... files loading okay with dropbox and evernote... what confused me is some files on Dropbox I marked for offline didn't load... but they were marked 2 years ago.. current ones show up

Gonna check your question... re pdf and evernote while offline... 

ok.. yes on android you can choose your pdf Reader for evernote 

Here is the thing to consider... I use two devices... with evernote,  you can mark a master folder for offline reading.... if you save a pdf file on one device,  it will automatically store locally on each device where you marked the folder for offline reading... True two way syncing 

With Dropbox,  if you mark a file for offline reading,  it will only store locally and you must set that file for offline reading for each device.. There doesn't appear to be an option to set an entire folder for syncing like evernote to allow full two way syncing... now invididual files marked on multiple devices will sync any changes... 

However,  I just discovered (thanks to this conversation)  an android program called Dropsync,  that will allow full two way syncing..... Im sure there's an IOS equivalent. 

"Dropsync lets you automatically sync and share unlimited files and folders with Dropbox and with your other devices. It is an ideal tool for photo sync, photo upload, music download, document and file backup, automatic file transfer, automatic file sharing between devices,...

New files in your device are instantly uploaded to Dropbox. New files in Dropbox are automatically downloaded onto your device. If you delete a file on one side, it will be deleted on the other side. It works across multiple devices (your phone and your tablet). If their folders are synced with the same Dropbox account, they will be kept in sync with each other.

This is how Dropbox desktop client works but it's not the same with the official Dropbox Android app. The Dropbox app is all manual. Dropsync is all about automation.

Two-way automatic sync should be an essential feature of the official Dropbox app itself since the beginning. For whatever reason it is not the case. Dropsync is here to fill the gap"

yes.....btw  Strathy just explained using the OCR feature of evernote  for indexing in the dojo discussion.... a powerful feature I haven't  used. 

Can't find GoodReader in Android Play store. Any free program like this?