My husband and I dated long distance for almost 7 years before we got married. He was in college in Florida, then moved to Atlanta and I was in Pennsylvania. In some ways it was like having the best of two worlds: the security and love of a relationship but the freedom of the single life. We talked two or three times a day on the phone for hours(this was before cell phones and cheap long distance plans, we were paying 30cents a minute) and visited each other every couple of months.
We were both allowed to date others during this time although we really didn't very much. Sometimes it was actually harder to get along when he was at home for the summer.
It was a very expensive relationship, but worth every penny. I think the long telephone conversations were vital, knowing everything about each others day built trust. We were also both secure in who we were as individuals and didn't rely on each other for our identity, self worth, or security.
It was very difficult and lonley at times. When we would see each other again, it was almost like we were strangers and had to re-evaluate if we actually liked each other in person. Fortunately the answer was always "yes". We have now been married for 15 years.