Why use TIFF? Seems pretty pointless, it's always better getting the shots due to having the space, than to not get them at all. I've never come across a review of a camera where there has been a noticeable improvement between the highest quality JPEG setting and TIFF.
I've never used TIFF personally, I've owned 3 Panasonic Lumix cameras with the option and never been near it. Just use the best JPEG option, probably "Fine" or something like that at the highest resolution setting.
On the Lumix FZ20 a TIFF is over 16MB and the best JPEG is about 2.5MB. Considering the massive difference in file-size you would be amazed that there is virtually no difference in actual image quality. By all means use TIFF sparingly for some epic shots that you might want blown up at A3 or something as you will get a very minute improvement, but that's it.
Some approx values for a Lumix 5MP camera with a 1GB card...
TIFF = 62
High Quality JPEG: 350+