In the artistic categories, more is always better. Period films always trump modern settings, and minimalism is disregarded in favor of opulence.
Let's start with Best Art Direction: basically set design, though it encompasses a lot more. I think that Revolutionary Road (though set in the 1960's) and The Dark Knight are too modern-looking for this category. The Dutchess is usually just the sort of movie that wins here, but it's few nominations and critical panning don't bode well. Same goes for Changeling, whose 1920's setting is better evoked with costumes than set design. Voters are often impressed when a film depicts two or more contrasting different eras or cultures, like Topsy Turvy's mix of Victorian England and Feudal Japan or Chicago's bleak prisons and flashy cabaret numbers. The film that achieves that best is Benjamin Button, which spans nearly a century of period settings.
The same rules apply to Costume Design, so we can eliminate Milk and Revolutionary Road as too modern. Australia (the film) makes its one and only appearance at the Oscars and against heavy competition, it's bound to loose. Again, The Dutchess looks good on paper, but I think it will be bested again by Benjamin Button. Along with a century of design, it also displays a century of fashion and I think the wide variety will give it the win.
By the way, Slumdog Millionaire's snub in the Costume and Art Direction categories are the year's most egregious oversights.
There are three nominees for Best Makeup: Benjamin Button, The Dark Knight, and Hellboy II. Once again, making characters look natural is often overlooked while heavy prosthetics and effects get the glory. The Dark Knight features not only The Joker's spooky clown makeup, but Two-Face's digitally-enhanced visage. Hellboy II has the most prosthetic work, but I think voters will gravitate towards the prestige of Benjamin Button. Even though a lot of the character effects are done with computer effects, it's very hard to tell where the makeup begins and the effects end and voters will give both awards to Benjamin Button.
The Cinematography category is a tough one this year. Changeling and The Reader had some nice compositions and lighting, but they're pretty straightforward. I don't know anyone who left The Dark Knight saying "The camera work was amazing!" There were plenty of other things going on that overshadowed its cinematography. Benjamin Button's cinematography was good and could net a win if the film rolls towards a sweep. It could also be the first win ever for a female Director of Photography. Slumdog Millionaire had some beautiful and expressive camera work and captured the color and energy of Mumbai - it wasn't concerned with making everything look beautiful all the time and didn't shy away from ugliness. I'm going to pick Slumdog by a very narrow margin.