what comes to mind for me with what you're seeking is that it's easy to do. just as easy as it is to go around india on next to nothing, it is also possible to live quite lavishly. the social & economic classes within the culture lend itself to just this.

so, take first or second class trains. i think you can take one with just space for two people in a car or for four people in a car first class, and i don't know in second, but this is a good opportunity for your father to sit and talk with indian business class folks, all of whom will speak english well. in first class they will serve you ice cream as a snack, your food is catered, etc. this is all second-had information, as i haven't traveled this way in india, but many friends have. you can travel long distances by train in india, so if you give attention to this, you can see things all over the place. the first and second classes are air-conditioned cars, so the noise, pollution, and even feeling of riding the train are diminished, and you will have your own washroom i think.

if you are at all interested in the dalai lama, you can request audience with him. he holds public audience and answers questions and talks. poke around online for a website~you will need to register in advance for this. i don't know about nice hotels in dharamsala, which is the larger city associated with the dalai lama (who actually lives in the smaller town of mcleod ganj), so for sure ask about that first.

the challenge you're facing is smooth, unobstructed walking surfaces for your father. much of india is littered with life, and it's commonplace to step over just about anything walking around-and stairs are common. perhaps even call a nice hotel in delhi and talk with someone there and get some ideas. maybe up-play your dad's challenges with walking so that you're in the frame of mind, 'better safe than sorry,' as you don't want to get to a hotel and find out it has 30 steps to climb and no lift. that can easily happen in india.

for in-town transportation, he will likely assume to take a taxi because it is familiar. i really recommend taking a spin in a rickshaw, and you can organize with a driver to pick you up at your hotel, and get his cell phone number so anytime you want a ride, you can call him and he will pick you up. if you start flagging one down on the road, your dad may lose his nerve about it, but if it comes to pick him up, he will likely be more receptive. when i say rickshaw, i mean the ones powered by motorbike~not the ones powered by a man pulling you. first of all, your dad would have trouble getting into it, as it is very high. secondly, it will wear on your conscience to sit there and watch this man pulling you if you realize that this job will soon kill him.

i can't really help with touristic must-sees, but i hope this is helpful.

namaste,
karin

hrrmmm. . . india is huge, and there is so much to see--everywhere you go. I'd recommend getting out of Delhi ASAP, as it's a big and noisey city and there are much nicer places. April/May time, the north should be nice from what I understand (currently i'm in the south and it's just getting hotter and hotter!)

Agra and the taj. . . eh, I guess it's a must see thing if you come to india (i did it!), but the town of agra sucks, a big tourist trap and not very nice.

I loved loved loved rishikesh. . . dharamsala is also supposed to be great. definitely take rickshaws all over; cheap, fun, and easy. In India though, as the poster above me mentioned, there are lots of stairs, and the streets have lives of their own. . . I'm not saying your dad isn't going to be okay, but just be prepared.

India = wonderful/amazing/I love it on my first trip here and already know i'm gonna be back. . . just remember to bargain for everything and have a blast!

I would actually recommend against the trains if you only have ten days. You do meet a lot of very friendly Indian people on the train, but they are very slow, almost always an hour or two late, and getting in and out of the train stations can be really hectic. Even first class is pretty rough around the edges, and you do not get your own washroom. Flights within India are very cheap(about the same as the train), but you can cover much more ground. Also, it is very easy and fairly cheap(about $20) to get a car and driver for the day.
I strongly recommend visiting Darjeeling, it's a beautiful small city with views of some really big mountains. Hassan down south is also really neat(old ruins), as is the entire state of Kerala. Good luck!