I am assuming that you are looking at doing a 1/32 or 1/24 scale layout based on the comments about the rally style car, etc. - but if you are potentially looking at an HO layout, specifically where the target class of cars can be something slower, like stock t-jets - the "around the room shelf" might be doable without getting yourself dizzy And as an added bonus, it would allow for a LOT of scenery options. :)
But on the larger scale(s) - I think I would have to recommend against doing a "full circle" do to the issues with following the action. Instead, I would think that it would make for a more enjoyable layout to have it tied to only two or three walls to make an L, J or U type shape - that would eliminate the need to spin completely around to follow the action. :)
Another option you could look at is to build something like the btaylor's "Dragon" track:
http://homeracingworld.us/viewtopic.php?f=32&t=11243And while I can't find where I saw the build for this track - this track is basically a vertical build that has a relatively small footprint:
(just food for thought! )
:D