In Terms of
- Development
- Maintenance
- Accessibility
- Usability
- Readability
- Print-ability
In Terms of
It all depends on how "Liquid" you make it.
Personally I like to make the length liquid but have everything wrapped in a static container div.
The key is going to be to "Code to your audience." If what you are using will work fine in a completely liquid layout (forums are a good example of this) and that's the way you want to go, great. (Just make sure you use the clear:both; attribute of css to prevent things from going beside each other.)
Development: only con is that you have to make sure things don't start moving it weird places.
Maintenance: Can be a pain because weird things can happen.
Accessibility: Depends on how good you are at making said layout. It can work very well or not well at all.
Usability: Shouldn't be a big deal.
Readability: Ahh, here's the tricky one. because people use different screen sizes this one can get really weird. (I use a 42" tv as my main monitor so pages that go 95% of the screen suck.) I personally like to have a set width because people will (hopefully) be logging on the place from more than one computer. a set width provides consistency between different screen sizes.
Printability: Shouldn't be a problem at all.