We have a day in our itinerary for the Blue Mountains. I've read many postings, and have narrowed things down to 3 options.
1. Oztrek tour (this features walk down Giants Staircase; how strenuous is that hike for arthiritc knees?)
2. Train to Katoomba with either Explorer Bus or trolly tour
3. Train to Katoomba with car rental
I would greatly appreciate feedback. Thanks.

Aren, because you only have 1 day to visit the Blue Mountains and arthritic knees, I would stick to the "general" sightseeing in the mountains. I would opt for a car, especially, if you are visiting outside of weekends or school holidays, when its much quieter. The drive out of Sydney on the motorway is pleasant, and easy. I would recommend the following sights...Echo Point & 3 sisters, the Cliff Drive, the village of Leura (art/antique shops & restaurants), then go up to Blackheath & drive down the valley (rainforest), or to Govetts & Evans Lookouts. (One of my favourite bush walks is on the road to Evans Lookout, and its called "Grand Canyon Walk" but its a strenous walk both down & up the gorge)
Also there is a Sky Cable and Scenic Railway, which takes you down into the valley, where you will find an easy level walking track, in amongst the bush & ferns, then afterwards get the scenic railway back up to the top station. I think these options would be best, especially with artritic knees.
There are other sights:- Like Little Hartley (historic village & gaol), and Mt.York where you can see the actual road & convict pick marks on the sandstone rocks, where the first "roads crossed the blue mountains".
Sorry to ramble on, but there is so much to see & do in the Blue Mountains, and its not all just in Katoomba. Have you thought of staying one night there?

I too have arthritic knees, but if you want to walk, one thing you can do is descend the Giants Staircase, then walk across the valley floor to the Scenic Railway (another alternative is the 'Sceniscender'), and take that back up to the top.

For a one-day trip, I would just hire a car and drive on up there from Sydney.

Hi, aren!

There are half a dozen different stairways to get from the top of the mountains to the valley floor, but, really, one is much like another -- in every case you're going to have some easy downhill-slope track, some steps, and a few ladder-like sections. In each case the descent involves about half-hour's walk. The Giant Stairway is perhaps marginally-easier than the others, but if you have doubts about your walking ability, I wouldn't risk it. There are other ways, as Alf has pointed out, to get to the valley floor (from where all trails are fairly level), and you may be wise to utilize both the Scenic Railway and the new Sceniscender. Not much point taking the Oztrek Tour and then backing out when you saw how far down it was!

Either of your last two options is okay -- the bus/trolley service frio=om katoomba Station stops right at the entrance to the Railway/Sceniscender complex. Your idea of training to Katoomba (or, actually, Leura) and THEN renting a car is a much better one than driving from Sydney.... it's a long way across the plains to the foot of the mountains, and the drive for that part of your journey is far from scenic. You might like to make the car rental even easier by leaving the train at Valley Heights and renting from Redicar, which is directly opposite Valley Heights Station -- easier and quicker than getting off at Leura and then trying to find the Redicar office!

Thanks to you all for your suggestions. I think the train/car rental option seems most appealing, but as it will be our first left-side driving experience, we may chicken out and take Explorer bus to scenic train stop.
Our dates for Sydney are August 5-8; does that change anyone's advice?
One day we will take the ferry to Manly and environs. One day Blue Mountains. One night at the Symphony (to be in the concert hall.) Many thanks to all who have posted to this site for great suggestions and ramblings. I hope the trip will be as much fun as the reading and preparing!
We are staying at the Lord Nelson Brewery Hotel in Sydney, so if the weather is bad we can just sit in the pub. If you're in the area, we'll be glad to buy you a beer!