I have a lot of different tracks that I have tried and used for quick carpet type show setups.
If you could find some old k-Line Super snap this is great RMT only sells up to 0-72 right now ask when larger stuff would be avaiable it is the old Super snap done by RMT
http://www.readymadetoys.com/susntruma520.html
I have used Gargraves but you have to do a bit of work to keep it laying flat, and it does not hold to a perfect circle tends to slip out a bit wider when used a lot better if screwed down for a layout then stays flat.
As for the Fastrak; I have a huge box of it comes with the sets and this would be the last choice for me for any layout or short term carpet layout;
To respond to the above comments
1, Looks: Very good. Best tie spacing/size in class. Strongly disagree the flat straight sides of the rail does not look like real rail and very bright.
2, Mechanical: Again, the best in class, able to withstand repeated use.
Wrong I have had a number of tabs come loose and not hold the track together in repeated use, the track tends to come loose in use as tabs wear with use.
3, Electrical: Very good, solid, and able to withstand repeated use.
Wrong some of the worst for this on the market, I have to put in lots of power jumpers for the temporary carpet use if any size for the layout. Small loop or oval sometimes OK but the tabs do not always hold tight and looses power someone I saw a family with a loop actually had burn marks in the carpet from the track arching with not staying tight together.
4, Cons: More noise compared to other, in class options. Rail looks: other options have better-looking rails. More noise there is nothing else on the market in track that is as noisy as this track, I never use it if I can help it. Yard storage track where nothing moves and do not need good electrical conduct that is all that I use mine for if a big show I am doing keep the track to small loops to reduce the problems but always have to go back in during the weekend and keep tighting up some joints they come loose in use.This track is really loud even on carpet.
Something you could consider is to take some track like Gargraves good price and mount it on large wood curves for a base cut out for 4x8 sheets of plywood. Cut as long as possible and screw track to this.(use some cork or sound deadening under it) and then some tabs and pins to hold the wood sheets together when joined. The Gargraves maintains excellent contact with the pins.
I had some of this for large show layouts but big and hard to take to shows when I found a lot of K-Line Super Snap I lvoe this stuff works great, good contact.
Have a large set up I do roll out a couple of rolls of green carpet and set up several loops of Supersnap in 12' x 22' space at several shows a year. Loops from 0-120 / 96 / 84?/ 72 and smaller loops.
If I run out have more trains a bigger display kids area for kids to run trains do a few loops of Fastrak but always problems every time with it coming apart! And keep it well away from other track because of the noise!