Some things you can do with GPS on your fishing trip include:
1. Patterning
2. Recording casting areas, scouted regions, and shoals
3. Plot exact coordinates of that 'perfect fishing spot' and go back whenever you'd like
4. Add your own journal, notes, and even digital pictures memorable locales
5. Create your own custom routes as well as maps
6. Use the GPS as a planner prior to voyaging off on the trip
7. Provide you with real-time navigation so you know where you are and where you are going
8. Conduct an analysis of your trip afterwards

That's just an inkling of what you can do with GPS on your trip! You can even use the tracking system to find out about those amusement parks and other points of interest even before you get to the fishing destination.

In addition to having a GPS system, it also helps to have a human guide especially in an area you are visiting for the first time. Guides have the advantage in that they are familiar with the area but also the fishing techniques that work or don't work in given areas and seasons of the year. Aside from expert advice and tips on where and how to best catch fish, you will also usually receive a delicious lunch as part of the package!

Here are some questions you can ask to 'interview' an appropriate guide for your trip:

1. What kind of fish you want to catch?
2. Are you looking for trophy fish, or to catch a bunch of fish?
3. The type of fish you want to catch.
4. Whether the guide has experience with the particular fish you are after.
5. Which technique(s) will the guide recommend that you utilize?

Based on these questions you need to decide if it's worth the price vis a vis the benefits of a guide. You can even avoid a commitment by simply utilizing a guide for a day, and spend the rest of you trip with your own intuition, expertise, and trusty GPS sidekick.