Well, I have a low-slung rustic ranch and in my opinion, anything but the real thing or a really good faux shake looks wrong (unless the house has been modernized--I'm in a pretty big 1950s subdivision so I see a lot). I don't get any weather where I live now so I am less concerned about durability than you might be. But the old Tudors...different story! You want faux slate! :P I've seen some good metal wood-look roofs on Tudors. Since they're taller you don't always get as close as you do on a ranch. But there's always a bit that dips low, where you can see it up close, isn't there? You might need to just drive around and see what others have used that works, or check with a historical district in your area an see what's recommended. Ask the old house forum here at GW. When I was looking at paint options for my Tudor a few homes ago (the POs had roofed it with nasty flat "architectural" shingles so I was stuck there) I drove around Indian Village in Detroit for inspiration--if you have a similarly cool old neighborhood locally, spend some time in it. (All I can say about the durability of the treated shingles vs untreated is that they'll probably last longer in a fire. Haha you'd hope so at least!) Do see if you can get any recs at the old house forum. I don't think they'd allow you to misshingle up a cool old house. Here is a link that might be useful: http://ths.gardenweb.com/forums/oldhouse/

Because the joints are not sealed, vinyl siding has a very high permeability rating over 40 perms (similar to the wood siding) so it is unlikely to trap moisture long enough to damage the old siding (I assume it is painted). Another issue is whether to put house wrap behind it which might further slow the drying of the wall to the outside. But we don't know the climate or the kind or amount of insulation so I won't try to guess. If appropriate for the wall design, you could use a highly permeable house wrap like Tyvek behind the vinyl siding but only if the old siding is painted. For the vinyl siding to be level it should be installed on a level surface. That can be achieved with reversed shingle or clapboard shims or vertical strapping but the floating vinyl may be more susceptible to damage, but I don't have first hand experience with that. It might be better to remove the old siding. You should also carefully consider how to detail the openings, facias and corner boards.

Thank you all for the excellent feedback regarding the siding.. I am definitely going to replace all the landscaping.. Do you have any suggestions for what it should replace it.. Perhaps visuals.. I've tried finding free software that I can upload my picture and play with different ideas but so far no luck

Thank you all for your comments. I am still so torn because the trim on the siding is rotting away, especially on the back of the house that faces north. Granted, this wood is probably 25-30 years old... I am concerned that it will begin to rot again, when new wood is replaced. Our window sills are rotted and even windows are rotted. I assume this is from rain and maybe it can't dry out enough on the sides because the houses are close together? I just hate to waste a huge chunk of money on painting/staining the existing siding and have it all go to waste. It is going to be $18k to do the hazmat removal of the lead peeling paint, replace rotted wood and then put new wood siding on the addition. It's not like this is a $5000 job... Another concern is that I just found out a lot of moisture gets into the walls and seeps out of the house? Is this true? From cooking and showering? So this can cause the paint to fail prematurely if there is no vapor barrier, which there wouldn't be, since the cedar is original to the house in 1918. I also have concerns about going over cedar with vinyl for the same reason. I am concerned that mold could build up under the new vapor barrier that they would put up... I remember one siding company said it is a bad idea to not remove the old siding and this may have been why. We have had issues with mold in various places like under the front porch, but once proper ventilation was installed, it went away. I just don't want to have everything sealed up to the point that no water vapor can escape and is encapsulated in between the layers of siding, causing mold growth. I'm probably over thinking it, but we are stuck in which ever direction we choose, and neither is "cheap".