How to use internal WP functions for custom menu items

I have an overall question about how others build custom menu’s in WordPress and add an “id=current” action to it. Because I have the idea that the way I do it, is not the best one. (To use an understatement) There must be a much better way.

It’s a bit hard to explain.
What I mean is that Worpdress can render it’s own menu’s with the help of <?php wp_list_pages( $args ); ?> or <?php wp_nav_menu( $args ); ?>
And when doing so, it can add a ‘current id’ tag to the concerning <li> tag in the menu.
So far so good.

My problem is that a lot of times I can’t use the WordPress internal function because every seperate <li> of the menu needs to be styled apart/unique (e.g. due to a unique background color, or a unique button width)
Example.
I can have a menu like this:

HTML

<ul id="navigation">
<li class="button1"><a>Button1</a></li>
<li class="button2"><a>Button2</a>
	<li class="button2"><a>Button2A</a></li>
	<li class="button2"><a>Button2B</a></li>
</li>
<li class="button3"><a>Button3</a></li>
<li class="button4"><a>Button4</a></li>
</ul>

CSS

ul#navigation {
    padding: 0;
    list-style-type: none;
    position: relative;
} 

#navigation li {
    display: block;
    float: left;
}

#navigation li.button1 {
	width: 135px;
	background-color: #284;
}
#navigation li.button2 {
	width: 120px;
	background-color: #f30;
}

#navigation li.button3 {
	width: 131px;
	background-color: #61a;
}
#navigation li.button4 {
	width: 145px;
	background-color: #d3e;
}

Usually I end up NOT using the internal WP functions, hard-coding this construction in the template. And of course this comes with the expected problems like:
– No flexibility in the menu (changing a page means changing the template)
– No automagical “currentpage-ID”

My question is more simple than the explanation ??
How do others solve this. It would be great to use the wp_list_pages or wp_nav_menu anyway. This would solve the “current page ID” problem at the same time.
If not possible, is there a way to create an ‘current page ID’ function anyway? (I mean, without using self made scripts)

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