I can't offer that much help here as the bulk of my family are either seasoned travelers or arm-chair travelers. I will post a link to my 'guide' if and when I ever do it! What I can say though, is that you cannot make them love this place if they don't want to or, even do want to and just don't. All you can do is make the transition as easy for them as possible and try not to apologize to them for things that are normal here. If they complain a lot, just be very matter-of-fact about it 'that's the way it is here'. It might also be useful to have a few reminders of anything back home that drives you or them mad up your sleeve, too. No place i perfect. Focus on the great history here, the beauty, etc. Is there anything you parents do like (sewing, trains, whatever) that might present an opportunity to explore here?
And as for the tea, well, my family lived in India for a few years so I grew up on the stuff anyway! Most tea shops have decent coffee as do pubs and restaurants.
Good luck!