After perusing through the answers, I noticed there were not very many technology based hacks. Here is a tech hack that I wished for the entirety of my semester abroad in Hong Kong, yet only recently figured out how to do. I am perplexed why Google has not solved this demanded and needed feature of Custom maps.

This hack is for the traveler without data access who wants to be able to quickly reference and locate predetermined spots/activities/notes on a mobile device map. This travel strategy minimizes planning time and maximizes flexibility/spontaneity.

Example:

Uses:
-Mobile Device (or printed paper)
-Google Custom Maps
-KML converter

1) Google for or create a custom map

Examples:

I co-created this for my trip to Japan: D&B Japan Trip Tokyo-Kyoto-Osaka
Create:

Hanoi - Google Maps
Find:

1.1) You can find many Google Custom maps like "Top Spots in Venice" or "Hanoi's Top TripAdvisor Attractions" freely created by other wonderful travelers. These maps often have a wealth of tidbits/tips on every location recorded in the notes section.

2) Copy URL by clicking the paper clip link button

3) Paste URL into http://maps.taurich.org/printmaps/ "Google Maps Link" textbox

4) Copy and Paste "&output=kml" to the end of the URL. (strCustomMapURL + "&output=kml"). Push submit.
Input:

4.1) Can also mess with settings like keep original icons (useful if you segmented the icons i.e. blue = bars, red = hostels (Hanoi - Google Maps)

Output:

5) Ctrl + P to bring up print screen. Change destination to "Save as PDF." Save as PDF. Download onto mobile device via email, Dropbox, etc. Reference throughout trip.
Save:

Access:

Be spontaneous - Traveling is an adventure!