Thanks for all the input everyone. In many ways I'm glad I don't have a never ending source of money to spend on camera equipment when I want to 'try' something new, otherwise I'd have a room full of the stuff, most of which I'd regret buying!
I think I now have a pretty reasonable grasp on what I want out of a camera set-up, and the result that will work best will being having two different set ups, sometime down the road. I'll admit I'm still a little bit afraid of making the step into 4x5. Having done alot of research on it, and reading all sorts of things about it, I really want to make the move, but I'm not completly set up to handle 4x5, and the cost of film is a little bit frightening too.
I think in the mean time I'll jump back into 35mm by getting myself a Nikon FM3A, and build up a three to four lens set for it (I can't see myself ever leting anything other than myself focus a camera again). It should do everything I need it to do for years to come, and I'll be able to become aquainted with all aspects of photography at a much higher level before jumping into large format a few years down the road.