I had a very pleasant interviewing experience overall. There were three stages in my case (and it sounds like in most cases):
1st round: Phone interview, resume review
I applied in mid-May and received an email asking to set up a time for a phone interview in mid- to late-June. The interviewer was an HR person on the east coast. The questions were easy since I knew my resume like the back of my hand. Be able to talk for at least 5 minutes about each thing that is on your resume. Don't bore them, either. For this interview, the HR rep basically asks you to go into more detail about things on your resume.
2nd round: Phone interview, behavioral analysis (two weeks later)
We've all had plenty of these before. "Tell me about a time when you failed, and what did you do about it?" A lot of those questions (four or five). There are TONS of example questions on plenty of websites; spend a few hours looking these up. Recall all of your experiences, and which ones would be useful for popular questions. Don't write a script - but have a general idea of where you can go for examples. This time the HR person was from Chicago (their central US office) I believe.
3rd round: On-site interview (two weeks later)
I was flown to a site other than Denver to interview, since there were closer locations to where I was living. Also, the location I visited had the soonest interview date set. The entire process was about 4-5 hours - two 1:1 interivews with executives of the company (much more laid back than the phone interviews, but they still asked a couple of behavioral questions each), and a more casual presentation given by an analyst and a consultant. It was nice to ask questions with two people who had just been through what I was going to go through. I hear that typically there are 5-10 candidates at each of these sessions, but I was only there during the morning session with one other candidate. Not that it really matters too much; the interviews are 1:1 anyway.
I received a call from the Denver recruiter extending an offer the next business day. The starting salary and signing/relocation bonuses were very generous, especially considering I was just out of college.
Overall tips:
1.) PREPARE! These interviews are a piece of cake if you know your resume, practice behavioral interview questions and answers, and are a clean, polite, friendly person.
2.) ASK QUESTIONS! Right before my on-site interview the recruiter I met with flat out told me that the interviewers love questions. Enough said. Just know what questions you should and shouldn't ask.
Accenture seems like the perfect place to work if you like to put the work in and be rewarded for it (read: bonuses/promotions). And you have to like to travel. Good luck!