Ideas/Advice for the Roof Rebuild

I need some advice about drawing up blueprints for a new roof on our house. Thanks to some shoddy workmanship on an addition before we bought the house we need to completely remove the existing roof (framing and all) and put a new solid roof over the whole house. I am trying to decide what kind of framing structure to use on the new roof. We are also doing a complete floor plan remodel on the interior of the house. I have attached the blueprint of the final product.

The dimensions of the house are what is making this somewhat difficult. The house if 42×50, so that would make for a larger than usual truss. We are also wanting to have an attic space that we can finish someday to add a couple of rooms and have vaulted ceilings in part of the house.

From the research that I have done, it seems like the simplest and best solution is to use a structural ridge beam to help support the new roof. This would allow us to leave the entire attic space open and would also simplify the construction process because we should be able to leave the ceilings up in the house until we are ready to redo them as well. It also adds strength to the house because half of the weight of the roof would be supported by the ridge beam instead of all of the weight resting on the exterior walls.

I have attached an outline of where the ridge beam would go as well as where the vaulted ceilings would be. Can anyone offer any advise or a better alternative to a ridge beam?

House Blueprint:

_{(source: bateswebdesign.com)}

Ridge Beam Blueprint:

_{(source: bateswebdesign.com)}

Current Roof:

_{(source: bateswebdesign.com)}