Deciding About Book Length, Etc.

So, yesterday on The Writing Spectacle, I talk a bit about what I'm currently doing.  I've pulled a forgotten manuscript out of the dank corners of my harddrive, shaken the dust off, and am reading it to get back into the swing of the story.  I'm still not ready to say which one, but I'd like to talk about a couple things regarding it.

I'm still not sure if this is one book or several.  It's already at 78K words and it's only 2/3rds of the way through the story.  Plus, I have ideas that need to be inserted throughout what I've already read through to make the story fuller and richer.  (I had an awesome idea last night as I was trying to sleep that I got up and wrote down.  Woohoo!)  That'll swell the story up to upgodly pages for a single title.  

I'm not super afraid of putting a big book out there.  Lord knows I have a few titles over 100K words out there already.  I just want to do what's right for this story.  

There are definite places where the story could be broken into three to make a trilogy.  Without making it too cliffhangery.  I hate stories that leave too much hanging from one book to the next.  

The genre could handle a single title of epic proportions.  It could also handle a trilogy.  

Decisions decisions.  

Any way I slice it, I'm still working toward having the whole story done before I decide.  It'll either be a behemoth or it'll release one after the other as a trilogy.  Which brings me around to another point...

Will the market bear paying for three separate books or would it be better to lay out a single book?  Personally, I like big books.  It's hard to hold them these days, but I manage, and if they're ebooks, even better.  I'd rather read one big book than three little books, especially when I have to pay for them.  But that's me, and I know I'm not the typical reader.

So what say you?