We have purchased a 1st class Eurail Select pass for our travels in Denmark and Sweden. We plan to take the X2000 from Goteborg to Stockholm. I've read that seat reservations are mandatory. How do I purchase that reservation? Do trains fill up? Also, is it possible to purchase other seat reservations at the same time? We will also take the train from Stockholm to Leksand for Midsummer festivities and from Leksand to Copenhagen after that weekend. I would appreciate any other advice about train travel in Sweden and Denmark, too.