At my first conference I was one of about 8,000 attendees; at my second, I was one of about 500. The most noticeable difference between the two was the food. At the large conference, the only food I received was at a special networking lunch I signed up for, and paid extra for. At this conference, there was food everywhere.
Each morning there was a continental breakfast. This was not "continental" in the sense of my (cheap) non-conference hotel, which was cereal, bananas, slightly stale muffins, and the opportunity to make Texas-shaped waffles; this was "continental" in the sense of coffee and danishes of plausibly European origins. More coffee would be served at the second session; no snacks, but then it was right before lunch.
Between the two afternoon sessions, tables were laid out featuring yet more coffee (obviously the caterers understood that attendees would be jet-lagged, and likely unused to waking up at 7 a.m. for several days in a row), and delicious fudgy chocolate brownies. There was an alternative to the brownies, but I ignored it.
The greatest surprise was at the poster session. These were over the dinner hour, and I expected people to be rushing through on their way to nourishment. Instead, there was an array of hors d'oeuvres, including mini kebobs, some little potato pancakes, and many triangular pieces of bread decorated with fancy flowers of butter.
Of course, there was more to the conference than just the food. There was the research, and networking (not well, but some) with other researchers, and getting the chance to present my own research. But I think the catering will be the most memorable part of the conference, and something by which future conferences will be judged. After all, I am still a graduate student, and entranced by free food.