Get thee a map of Holland!
Den Bosch is also known as s-Hertogenbosch, about an hour by train from Amsterdam. It's also very charming, like Haarlem.
If you look at the map, the Wadden & Frisian Islands are way up north, so you gotta make sure you already have accommodation booked there, as jaykay mentioned. As for the beach... well, the only beach I visited was at Scheveningen. It's definitely worth a visit. You probably have to take a train to Den Haag, and then a bus/tram to Scheveningen (apologies that I don't remember which bus/tram, but a good guidebook should be able to tell you ways of getting there).
Amsterdam-Den Haag HS is about 40-45 mins, to Den Haag Centraal is about 50mins to an hour.
If I wanted to take a day trip to get out the beach and just kind of people watch and check out the beach, where should I go? And how to get there form Amsterdam. In other words, I don't want to go down and lay in the Sun or go in the water, but would like to go a beach area (form Amsterdam, for the day) and check out the scene.
Zandvoort is 25 min. by train. My Dutch friends sheepishly refer to this town as the "South Beach" of The Netherlands (it is actually due west of Amsterdam). It is a popular getaway in the summer especially if you visit during one of the rare hot days of July and August. There is a casino, some restaurants and bars and a beach scene to please all types of visitors. It has been awhile since I was there so you might want to Google "Zandvoort" for more current information.