Roller Coaster Simulator Game Help! Which is a good Roller Coaster game?

I've been feeling rather bored lately, and Sims and Minecraft aren't doing it for me anymore. So I wanted to Build some roller coasters.(yeah… I know, really random) However, I know of very little in the field of rollercoaster simulations/building games. I heard of Thrillville: Off the Rails. A theme park creator following a simple yet easy story line of build the best park. The game looks and feels pretty good and the interface is easy. You can even ride your rides with a P.o.V shot, it's really cool!

Then I heard of the Roller Coaster Tycoon series. Most recently RCT:2. It has even MORE freedom than Thrillville, yet more simple, using sprites instead. However, you can't enjoy ridding your creations at all which is a little bit of a buzz kill and it plays more like a heavy plot game… Meaning there's no time to fudge around and have fun… As in I'm not sure about a more sand-boxy mode for the game. I NEED that.

So I suppose what I'm asking is, What's a good Roller Coaster simulator/Theme Park Simulator for Windows. A game that has a more sandbox feel and the ability to ride the coasters you make or more enjoy-ability to your creations. You guys know what I'm saying?

Is Thrillville really the best game for fitting this? I don't know that's why I'm asking. I don't care about graphics, I just need it For Windows. I have Window 7 and I'm not too sure about anything else.

Any help you can give will be welcome.

Rollercoaster Tycoon 3 allows you to ride the rides if that's what you are wanting the most. It's also rather fun and addicting with some interesting cheats that adds to gameplay, like the buggy cheat that gives you a dune buggy to drive around your park. And the expansion packs allow you to have a water park if you want and other such things. The game also looks amazing which is a bonus!

The best one is the Rollercoaster Tycoon 3. It is the best game. If you need other tycoon games then you can refer the source. Enjoy!