Sounds like your in the same boat as me. you have an older farm house, with a super steep roof, yankee gutters and cedar shake.
Now for the BAD BAD BAD news...
full replacement means a complete tearoff. including the cedar shake and redo it with plywood. then tar paper and shingles of your choice. how high is it?
Make sure, who ever you hire has atleast 1 mill in insurance.
Also, let us know who you go with and what they charged =)
oh and one last thing, industry standard is ice and water shield, one row along the roofs lower edge.
If you can, opt to have two rows put on, the roofer might tell ya its not needed, but is he gonna pay the thousands of dollars damage in 5 yrs when the gutters back up and the water goes under the shingles and over the first row? no he isnt. might cost a couple hundred more but its worth it.
Ice and water shield is a roll.. basically, its like a giant ashphalt shingle, 2ft wide, 25ft long ( might be shorter) with an adhesive backing... you put this on first then tar paper over it... but its better to have two rows instead of one, giving u effectively 4ft wide of ice and water shield.
Also, who ever you choose, be sure to buy everyone tim hortons coffee in the morning, or pizza for lunch or something, youll get a better job out of it.