Word choice is hard. I guess that it falls under the heading of style -- some people prefer to write in a more flowery style, others like to be very stripped-down with only the minimum needed to tell the story. Generally I prefer a simpler, more direct style as a reader, but I have to fight to keep from overloading my own prose with run-on sentences (my betas often tell me to break up my interminable sentences -- and they're right!) and convoluted ways of avoiding using the perfectly good words "was" and "said".

Up to a point, you really have no control over how your reader reacts to your writing style, just like you have no way of knowing if they have a knee-jerk "hate!" response to one of the tropes that you absolutely love and like to use. I have trouble reading a lot of fantasy novels because they use a writing style that is more lush, flowery and descriptive than what I personally prefer to read, but it doesn't make them inherently bad. Some readers prefer that genre, though, because they like beautiful, creative language.

But it's only true up to a point, because like you said, the words you use should be the right ones for the job, and if you're turning off a lot of readers with your prose, then it's not doing your story any favors and it's something that need to be worked on.

I sometimes struggle with this when I beta for people. I don't have any trouble pointing out words that are factually wrong for the way they're being used, but it's a lot harder for me when I hit a word that simply doesn't seem to fit with the tone of the scene -- like your example of the word "giggle", where it's too frivolous a word for a serious scene. But it's hard for me to decide if it's just a matter of personal opinion or something that I really ought to point out to the person I'm beta'ing for. (Usually I point it out but include the caveat that my opinion might not be the only way of viewing it ...)

Along those lines, it's not so hard for me to find a word that means what I want it to mean -- the hard thing is making sure that the words I'm using have the right "feeling" for the scene. And I don't really have a formula for it, at all. For me, it's very much under the "art" part of writing as an art form; it's just a matter of how it feels to me, how the scene makes me feel when I re-read it, whether there's anything that is throwing me out of it or whether I get caught up in it.

One thing I have learned through posting and re-reading my fanfic is that if there's a turn of phrase that seems awkward or strained or out of place to me, I need to change it, because it really won't look any better the fifth time than the first. *g*

I love the whole "less is more" discussion that you and tari_roo are having, because I think that's an excellent point -- it is easier to add than to cut! I often have to stop and remind myself that I don't have to get it right on the first draft, I just have to get the gist of it down. It's okay to go back and fix it later.