Question 1: Does it look good at that size?

Your image will look good because most people will only look at it from afar. If it is at a trade show and depending on where exactly it is, no one may be able to get close to the image.

Much more about this can be read here: How do I generate high quality prints with an ink jet printer?

• Using Patrick Hurley's calculation of your image having 3456 pixels in both directions and thus at 8 foot a resolution of 36 PPI.
• Combining this with the data and formula provided in the above answer, we have
• Resolving power P = 0.00029

• We get the viewing distance D:

  D = 1 / (P * PPI) = 1 / (0.00029 * 36 PPI) = 96 inches = 2.4 m

Question 2: Does the format being TIFF instead of JPEG make it easier to "blow up" to that size?

Yes, TIFF can be lossless and JPEG never is. Additionally TIFF can also be 16bit, which won't help with printing but will help with interpolating to a higher resolution.

However, larger viewing distance would probably also give you good results from JPEG (see question1). Overall, TIFF is the preferred format by most printers and graphic designers. The only thing it is not good for is web, where size matters a lot and TIFF is just too large.

As Michael Clark pointed out, once you go to JPEG you loose information. TIFF only makes sense if you started in a lossless format like Canon's raw format .cr2.