Apr 1, 2015 - 5:51 AM
Welcome to our website! I wouldn't have recommended a Eurail Pass for your plans, but now that you have one I'm sure we'll find a way to make the best of it. Here's a map to check what's included for free and discounted. Lyon to Interlaken is free, apart from seat reservations in case you travel with trains that require them. Swiss trains do not require them, French high speed trains do. Please see here and here for details.
You don't need point to point tickets to go to Interlaken, because you have a pass. All you possibly need is seat reservations for the French leg from Lyon to Geneva. Since this is all last-minute you may want to go to the nearest rail station and get them there, instead of figuring this out online.
You do need point to point tickets if you want to travel on routes which are not free, into the Jungfrau region for example. In that case you show your pass at the ticket window to get a 25% discount on these tickets. Some other routes will provide a 50% discount. The boats from Interlaken onto the lake are free with your pass.