Hey Russ,
If I am reading correctly your concern is that you don't want to have to re-read posts that you have already read (which new posts are indicated by the "new" tags on each newer post since you visited).
The phpBB board uses a similar methodology. It will tag when there are new posts since you last visited, but it also adds post serially (like here) but lists all of the posts in one viewing, preventing the need to click on each 'heading' to view the response.
I'm not 100% sure, but most BB's will allow some sort of subscription to a post as well, sending a notice or sometimes even the new posts once it is logged into the Database.
I'm leaning towards phpBB for my website, once I set it up. I've got a friend who is familiar with it so it should make it a little easier for use.
Craig
Somewhere up in NoCo