For our stay in Europe, we purchased a 10-segment Eurail Select Pass that was valid in 4 countries (France, Switzerland, Austria, and Italy) over a period of two months.
Our research into this topic showed that our route was cost effective for the ten most expensive rail segments out of the fourteen we were planning to take. However, since purchasing our rail pass we realized one little error that we did not account for in our first analysis, and that it is the major headache (and cost) that comes with making Eurail reservations for seat assignments ahead of time.
After making our reservations, we realized that there are a lot of subtle intricacies required when booking reservations with a Eurail Pass. Since the need for reservations and their corresponding fees aren't necessary for everyone, this guide was born. For those like us who are traveling during peak season or are uneasy with winging it for popular rail routes, this one is for you.