I first spoke to a recruiter at a university career fair. He was recruiting only for technical positions, but he offered to take my resume anyway and pass it on. I was contacted a few weeks later by HR to set up a phone interview. The phone interview consisted of a few basic background questions about my experience and relevant skills. I then received an analytical skills test via email, dealing with website data points such as clicks and impressions for various accounts. It was somewhat complex, but I completed it within a week. I was then contacted again and invited to a 2.5 hours panel interview. I met with 4 mid to senior level employees, each in a different marketing areas (e.g. SEO, site content, product management, partnerships). Each had previously worked with new hires in the position I was interviewing for, so they were able to answer any questions I had. Finally, I was invited one final time, and met with one senior employee. This was a short interview, about 30 minutes, during which I asked the majority of the questions. I was contacted about a week later with an offer, and given 5 days to make a decision. During that time, I spoke with two HR people about the specifics of the offer before I accepted.
Overall, it was a pleasant experience. Everyone who I met/spoke with was extremely nice and seemed to genuinely like working at TripAdvisor. I had no difficulty getting prompt responses via phone or email. Although the process in total was long (3+ months), there was little lag time between each individual portion of the interview process.
The only thing missing was maybe a quick tour of the office, which may be a selling point for potential hires. I did not see the whole complex, which I have heard is quite nice and has many unique amenities.