I am suffering from lack of information. And therefore have two answers based on two possible outcomes...
I don't know how bad the rot is. You at first say Minor... So the first thing you should actually do is hire a home inspector yourself. Now as a warning, whatever the home inspector finds will all of the sudden become a "known material defect" and therefore have to be disclosed when you sell. But it gives you two possibilities:
1) If (s)he says it's not so minor, and it's of serious concern... that is what your potential buyers are going to hear from their home inspector, they won't move ahead from that point. If that's what you hear... then no jaccuzi for you, everyone else below is absolutely right.
2) If you hire a home inspector, and they aren't worried about it, turn the jets on high and here's why:
You don't ever hear the saying, or read the statistics that sills and roofs sell houses. The saying is that Kitchens and bathrooms sell houses.
The moment you say "structural" people get worried (as you can read below). Are you a structural engineer? Have you had a structural engineer look at it?
Fix up the bathroom, and when your'e redy to sell, be sure to disclose that some wood on the sill is suspected to be rotting (show them the area of concern), and disclose any material defects you know of, and put it on a Sellers Disclosure statement to give to your agent. Also with the roof, if it's been leaking you might as well fix it, you'd have to disclose the leaking. If it's just old but there haven't been any problems, then disclose the age of the roof and that there haven't been any problems. You're not planning on selling this as a new construction are you? Of course not, this is Greater Boston. Homes here are old, it's part of their charm.