Off the top of my head, only two templates use tables at all and they should be cMap and Market. This is due to the persistence of legacy browsers and having to support tens of thousands of users using thousands of different themes and plugins all coded with varying levels of skill, self included. The use of tables in these two templates is primarily to support the columnar presentation within each entry. Certain legacy browsers had severe issues with dealing with floats properly. So, only the most basic structure is formed by the table the rest of the elements do not use tables at all and are very easily styled and easily overridden. Personally, I do not like using tables in this manner, but with these two templates it was near necessity/support.
Now, with that said … I’ve been slowly removing support for legacy browsers following the footsteps of Google, Facebook and WordPress. Version 3 of both those templates will have tables removed and legacy browser support completely removed [ie. some of the validation issue you expressed concern over in another forum thread].