For the TS-E 17 you will def need a tripod for about very shot as it is quite time intense to set up and you need to be quite precise when setting up ... This is one of worst lenses for handheld shooting ...
As someone who owns and uses the 17 and 24, I can tell you that you are incorrect as it pertains to the OP's question. If you are, for example, in a field of flowers and are trying to alter the plane of focus to achieve what appears to be infinite focus from near foreground to background then, yes, you absolutely need a tripod and preferably a DSLR with live view to aid with focusing. This technique involves TILTING the lens.
If you are shooting architecture and simply want to avoid the obnoxious perspective distortion that comes with pointing an ultra wide angle lens up or down then no tripod is necessary. You simply hold the camera level, SHIFT the lens up or down, focus like you normally would (manually, of course) and press the shutter button. It is not an iterative process like tilting. The only reason you would need a tripod is lack of light, a situation which affects non tilt-shifts as well.
You can correct perspective distortion in software but this isn't an ideal work around. Correcting in software necessarily involves cropping away part of the original image. This can dramatically reduce a lens' effective angle of view making it very difficult to compose in the field. The more the lens is pointed up, the narrower the final angle of view becomes after correction. (IOW, your 17mm lens may provide you with a post-correction 35mm angle of view.) But you can always stitch multiple images together to compensate, right? If you've tried you know that it's not as easy as it sounds if the images being stitched contain severe perspective distortion. And I guarantee that the time you "save" by not having to turn a shift knob and manually focus is more than lost in front of the computer.
Anyway, I'm not arguing that everyone needs a tilt-shift but there are always misconceptions about them when a discussion like this one comes up. They are a unique tool particularly well suited to photographing architecture.
Another solution is to use the 16-35 and just leave the perspective distortion uncorrected. Trey Ratcliff does this all the time with his 14-24. It drives me crazy but there are many people that don't seem to notice or care.