Simply put, I'm trying to think up a system that allows you to enter the same areas at daytime, and also at night.
I don't mean having a clock system, but like...there's always such a different feel to towns and fields when it's at night.
I want some form of changing time, but the player should experience it, not an event driven "it's night now" sequence.

Night just brings out so much atmosphere, I'd really like to hear your ideas of the perfect system.

(My brain is tired today, tell me if this is confusing)

I've done the day/night system before, but completely via eventing.
What I did is simply created two versions of all maps in the game where the player would "experience night", and in the areas where you could only enter during the daytime, I wouldn't have to create a night map for those areas.
The day/night system was based on where the player was in the story (because that particular game was mostly linear, it was easier to manage without needing scripts).
Maybe that helps a little? =]

Yeah I've done something like that, but I think what I'm going for is the player having a little bit more control over the time.

I guess I want two things: That feeling of going against the norm and going on your adventure in the dark, and also that ominous feeling that you're in the middle of a field and night has fallen, danger.

Hm, perhaps I'm going for a really vague idea.

In the middle of a field and night has fallen... ominous feeling...
Sounds a lot like Zelda, Hyrule area. XD

I get what you mean though. It's somewhat vague, but at the same time, what were you meaning in terms of giving players more control over that feature? 0.o

A day/night system could be done via map transferring.

Each map transferred increases time an increment. Now, the player can control the time by going over maps, allowing more power on what time certain things are. Intricacy can be added where you feel appropriate.

Also, you could just have day always in one area, dawn always in another, etc. They sort of used that in Final Fantasy 9, though I admit it was more for aesthetic reasons.

Otherwise it's up to you how else to do it. These are the most appropriate ways I can think of outside of some sort of clock system, where you can alter the clock speed in certain areas.

That seems like a cool idea.

What I meant by giving the player control was like...well for example, in Wind Waker. You have to play the song to make it nighttime, and then you hide and wait for the girl to stay at the shop. You chose to stay there at night and wait. I don't know, it just gives me a good feeling to be voluntarily deciding to stay up at night in a game. I feel like a secret agent...except less lame of an idea.

You could always just make a menu command (or an item, or a skill, etc) that changes the time.

I've got a pretty good system (it pauses when you call up party menus and the like and does do something where stores are closed at night), but if you're looking for different enemies, that is kinda the only way to do it (unless you have touch monster battles, in which case after a certain hour you can just set a different encounter. You could also make more enemies running around by setting some events to only appear at night.

I like that system. And I would only use touch monster system, cause random battles frustrate me.

Do you have a script for it?

My own system features a script-based core which essentially manages the screen tone according to the time of the day (and also the day of the year, with longer nights during winter and shorter ones during summer). It also updates a bunch of variables and switches which can in turn be used to make events appear only/behave differently at given hours/during nighttime/on given days of the week... Thus you have a wide range of choices to extensively tweak events according to time; simply by modifying the time variable (time doesn't flow automatically, it's entirely event-controlled, i.e. if the player remains idle for half an hour not a minute has passed, but they might also carry out actions that will take several hours at once, like crafting a weapon - it's all up to the game-maker -- also, even though not necessarily relevant, it's technically possible to go back into time). From there, it's all a matter of creativity and eventing skills, but then you can do virtually anything.

There are multiple ways to do this, but the one to give the player the most control is the one in Elder Scrolls IV: Oblivion. You have a variable called "time of day". It has 24. If the variable is larger than 24, just subtract 24, so it rechecks itself. Basically have it where people can rest, thus affecting the time of day. If you want realism, you could even make it where you can't rest if you have so much energy to where you aren't tired.

If you want to see more about the system, try searching for Oblivion's rest system.

Unless it adds something different, I don't think Day/Night system should be used. If there are more/stronger monsters at night and you can't visit shops during that time - it's cool. But if it's just for aesthetics - please don't. For example - Titan's Quest. Sure, it has day and night cycles which are made to ANNOY ME and that's it.

At certain points in the game it is required that the events take place at night.

I might just do it the cheap way by using events, if you find a bed you can sleep and wake up at night.