Like SSN688 we recently had new roof and gutters installed (last summer). We got architectural shingles (good shingles, just can't remember the exact make and model). We did not have to replace any fascia, although we did have the fascia, eaves, and gables painted (full brick raised ranch, on which we replaced the windows this year, so fascia, eaves, and gables are just about the only surfaces that require painting). Our decking was on the thin side, compared to today's materials (home built around 1970) so we had another layer of roof decking added on top of our existing. We upgraded from 5" to 6" gutters (seamless aluminum). We had something like this installed for leaf protection:http://www.guttersupply.com/p-Leaf-Defe ... 7AodzC8Akw
If you have anything besides straight gutter runs (inside corners, outside corners, etc), be sure that your installer (if you get something for leaf protection like I linked above) does the corner details correctly. Depending on the details (say an inside corner with a splash guard installed on top of the front of the gutter), it can be hard to get the screen (or whatever material is used) installed correctly. If the material normally overlaps the front of the gutter, it might not be able to because of the splash guard.
I don't have any direct experience with metal roofs, but as another poster indicated earlier, I would lean towards one of the hidden fastener solutions rather than the screw-through-the-metal solution. My BIL installs the screw-through-the-metal roofing (and has it on his house), so my concerns might be overblown. However, it makes sense to me that you would be more likely to have a leak with hundreds of screws through your roofing than with no screws through it.
Whatever type of roofing you get, I would recommend a complete tearoff (i.e. don't have the new roofing installed on top of the existing roofing). Supposedly it is acceptable to put new shingles on top of old (to a maximum depth of two layers total), but I never see that recommended. I'm sure that it can save some money, but I would feel better with the roof installed on a clean surface.
If you have any flashing, try to understand what properly installed flashing looks like. Hint: It probably does not look like a continuous band of aluminum (or some other metal) with gobs of silicone caulk on the top edge. We ended up taking down part of an unused (and poorly flashed) chimney so our job did not require any flashing work at all. One less "skills required" work item, one less thing to possibly go wrong.