I personally 'rank' my full day interviews. I put them off until I have a good sample of companies lined up. Then I line up my 'best' company first, and the 'worst' company last. Basically, the goal is that by the time I get to the company i'm not as interested in, I have an offer from another one. That way I can frankly tender my resignation in before I get to that interview. I may or may not complete the last interviews depending.