What's the best way of reading long txt documents?

Hi! I have a long book in txt format, broken into 3 separate files, that I would like to read. But each file is probably over 100 pages, and I would like to hear if someone has any suggestions to an app that would let me read this without too much of a hassle.
I first opened it in Text Edit on Mac, but it's really hard to locate the spot I left of when last reading it, if I close Text Edit in the meantime. So that's pretty mych out of the question, I think.
So then I put it in a dropbox folder and figured I might be able to export it to iBooks on my iPhone, but either dropbox or iBookks wont let me do that. AThe option to export to iBooks when trying to do that from dropbox doesn't appear in the export options.
So is there any other good apps for reading long txt documents, either on Mac or iPhone, both works for me! I would prefer an app that will remember where I last left of reading, or that will easily let me pick the right page number.
Any ideas?
I have Dolphin Easy Reader installed on my iPhone, but it didn't seem like I could export to it either from dropbox.
All suggestions is received with great thanks, cause I would really like to read this book soon, but with my existing apps on both platforms, this seems to be quite a struggle.
Cliff