This is not a DIY project for me. Tree limb fell and punched 2 4-5" holes in roof over attic space. Estimator said rafters were splintered. Estimate was $1700. Does this sound reasonable?

If the damage was such that some rafters were damaged and need to be replaced or sistered, then $1,700 is a fair price for that amount of work.

You are going to have shingles and felt removed from the damaged area, replace some roof decking and the repairs to the rafters. On reinstall, the new shingles will have to be woven in with the old.

Sounds right to me, if you have any paint or spare roofing sitting around, volunteer it. They may not need the paint, depends on the extent of damage.

Do yourself a huge, no gigantic favor and always do your own estimates. Never agree to any estimate that you did not give without checking the situation first. Without seeing the damage one can not tell, it could be more or less, and that's no joke.