There was a novel called "Dreadnought" which featured a 320 meter, 3-nacelled Federation-Class Starship.
I noticed it had no visible bridge, just a sensor dome up-top. Was that to avoid a visible bridge that could easily be blown-away? (The bridge I assume was buried deep inside the ship)
Also, with the third nacelle mounted on top of the saucer section, I would assume after a seperation, the saucer itself could go to warp?
CuttingEdge100
The novel "Dreadnought" borrowed, liberally, from the Franz Joseph design concepts (see the "Star Trek Technical Manual," etc) but tried to make it more of an experimental concept and less of a "real part of starfleet" (perhaps to explain why this was never really mentioned on-screen?). It seemed to treat the idea of a dreadnought as sort of anathema to the "official Roddenberrian" line he started putting forward late in his life about Starfleet not being military.
Personally, when I read the novel I accepted that what I was looking at was the FJ design. The novel wasn't terribly great, but it was enjoyable light reading... ie, I don't accept it as canon anyway. As far as I'm concerned, the "real" FJ ships were really there, and were used in pretty much the way that the 70s/80s fan works postulated (ie, as fleet flagships which were permanently assigned to a support role to each starbase during peacetime).
One of FJ's ideas with this ship was to put the bridge into a more practical (ie, safer) location... not out in the open where it's the most obvious target on the ship. So he replaced the topside bridge dome with another sensor dome just like on the underside, and stated that the bridge was in the very center of the primary hull.
The later fan-works (including a really nice set of blueprint which I also have, like a few other folks here) established this. Of course, there's a lot of question now as to whether or not any of that is "official canon" anymore... I prefer that to most of what I've seen in the later "official" works, so if I had to choose, I'd say that the dreadnoughts are part of the "real" Trek history, just as FJ drew them up initially.
EDIT: For more info on this design, check this link out.
http://www.cygnus-x1.net/links/lcars/uss-federation-class-dreadnought.php