The only companies I can think of at the moment are http://www.unitedvacations.co.uk who do free internal flights and Virgin holidays.

luci

I'm not sure on the companies that offer this trip but a word of warning on Memphis for your parents.

Graceland is magnificent, well worth a visit and with the ticket options available they could easily spend 3/4 of a day there.

Aside from that Memphis itself is a very industrial city. Beale Street is nice for an hour or so, grab a beer and listen to the music but aside from that there isn't a great deal more to do in the city. Sun Studio is worth a visit but is a half hour visit at best.

It is a personal view (although shared by quite a few people I know who have been) but I would say a day and night is ample time to see the city and move on. We were there for 2 nights, although staying outside the city and we were struggling for things to do once we had been to Graceland.

Just my thoughts, hope they help.

I also agree wholeheartedly with the previous poster re Memphis.

We recently visited Nashville TN, and decided to visit Graceland for a day trip, which if they have access to a car is quite enjoyable, we completed our visit to Memphis by visiting Beale Street.