I think 5alive may be thinking of carhire3000. I believe they are also associated with an Australian counterpart which is called traveljigsaw.com.au. They will include all insurance, sometimes they can get the dropoff fee waived, sometimes not.

OK, will do some checking re rentals for 'foreign folk'. If half the fun of travel is the planning then I'm having heaps of fun!
(Denver friend is working 5 days a week so that gets prohibitive, we plan weekend excursions, if I ever get there ha ha!)

OK I did a check of rental prices through traveljigsaw and found a car for one week, San Fran to Denver, for $US183, but am waiting to hear what the one-way add on fee might be.

With regards the Zephyr train - how long does it stop at places along the way, as in how much of a 'get off an walk around' opportunity would there be en route from San Fran to Denver? And can you please confirm (I'm a bit confused) - in coach you pay extra for meals, and in a 'roomette' they are incuded, right?