For me, the gaming side of waymarking is seeing the grid fill up - the challenge of coming up with a location for a difficult category. I love to search out new places and post them. It's also a way to share spots with folks who have a common interest, such as a specific type of architecture, or something like trains, hiking, etc.
I use the visit aspect of the site when I'm going to be travelling somewhere. I find locations that I didn't know about and might want to visit - local parks, museums, sculpture... I use the independent food categories to look for possible spots to stop and eat on a road trip - ice cream parlors, diners, pizza restaurants (lots of the best little indie places don't have Websites)...
What is great about waymarking is that if you ask any waymarker why they waymark and how they use the Website you'll likely get a different answer - "for the history" "to fill the grid" "to find cool places" "as a database for my vacation spots"... You have to stick around awhile and experiment and you'll find the perfect way to use waymarking for you.
I have a beginner's guide on my Website that you might be interested in. It walks people through how to post waymarks, log visits, etc. Hope that helps.