A while back, I asked very similar question. My current story is really a collection of shorts that so far is looking like it will be hideously long.
Good news Trop... At 1 per week, you've got content through September
Most of these are right around 2500 to 4000 words, and are a one sitting deal. The one going up today is part 2 of 4 of this particular story. I was lucky in that I found some places to break it up where it wouldn't really interrupt the flow, though the last part had to be quite a bit longer than the others. Sometime in July there is another 4 parter that didn't really have any clean spots to break it.
As a reader, I would prefer to read it all at once. That includes the last three Harry Potter novels BTW, so I may be outside the norm in that regard. The girlfriend is just the opposite. she reads all the time, but not for more than an hour or two at a time. She likes to make it last.
If a story is really long on here, I'll copy it to Word then highlight the parts I've read so I know where I left off if I have to stop and come back later.
My new player guide is broken up into pages that are about 1 page long in Word. The reason being, most people will see a huge page of text and think it's too long to get through, while that same text split into smaller pages, seems more manageable.
So, after all this, I'd say split it of you have a spot to break it cleanly, but ultimately, if there is no way to do that, then put it all in at once.
Guide for new players is now (mostly) updated for Issue 12. Link is the website in my profile.