I contacted and visited every department/professors I was interested in (only 4 programs, though). As I'm an international applicant, that definitely helped in every aspect of my application.
Some of the benefits I can list:
- The professors could see that I was serious about the type of study I wanted to pursue (one eventually said, in these very words: "I'm impressed that you're taking the time, effort and expense to visit our department")
- It definitely helped on my decisions to what school would be my first and second choice
- I was able to write a SOP that was very very specific and tailored for each school/department
- While visiting a professor, in some cases others professors became interested in talking with me (always remember to send an email to graduate admissions office as well!). In one program, this "second professor" became my first choice in that school and I realized my first choice professor was a bit rude.
- Besides the meet with potential advisors, you get to see the atmosphere of the city, talk with some others grad students and so on.
- You end up having someone to email when you're desperate about your decision and it's March already.
I couldn't see myself applying to a school without making a contact whatsoever with a professor. If you can, I would visit the professors you're interested in.