Hi, I graduated from Leeds Uni last year and am still living in Leeds, I loved both the university and the city, and would definitely recommend it. (I am Janh's dd1 by the way, there aren't two of us!)
I think that in terms of attending open days and getting a general "feel" for a university/ city, he would be better going on his own, although as has already been suggested, you could take him there, then leave him to his own devices and have a look round yourself. I found that at the open days I attended on my own, I asked a lot more questions and was more willing to talk to other people.
Leeds University itself is between 5 and 15 minutes walk from the city centre, but the accommodation varies enormously, from the on-campus halls thatYorkiegirl lived in, where you can literally roll out of bed and into uni, to Bodington, where I lived, which was massive, with brilliant facilities, but 4 miles out of Leeds - with traffic, that meant it took about 45 minutes to get in and out of uni! And led to a couple of missed lectures, I have to say, simply because I couldn't be bothered to spend an hour and a half on a bus to go to a one-hour lecture.(sorry Mum!)
Where I'm from originally is only about 40 miles from Leeds - just over an hour in the car and about 2 hours on public transport, and I loved the fact that I could decide to go home on the spur of the moment, but loads of my friends were from further afield and they never felt that they were too far from home as Leeds has really good public transport links with the rest of the country - Leeds to London on the train is just over 2 hours.
Sorry, I've gone on for ages! but if your ds has any further questions about Leeds, or universities and open days in general, I'd be happy to try and answer them.