I am taking this from Bob Sehlinger's Unofficial Guide to WDW.You must be a resort guest and possess a multi-day pass. The cost is $12 and allows you to stay in the parks and ride the "premium rides " ( Space Mt., Splash Mt,Buzz Lightyear, HM, BTMR, Country Bear Jamboree and Tommorowland Transit Authority with little or no wait, but I assume you have read some of the other posts and found out the short lines are not always the case.. Also seasonal and annual passports are included in this eligibility. I have never done an E-night because the program was not in existence the last time I went and I had a young child then. I believe you purchase a voucher at Guest Relations in the park. I'm not sure if you can buy them at your hotel. I'm sure someone else can elaborate. There are also only certain nights that are E-ride nights. For more info you can go to Allearsnet.com.E-ride nights officially end for the season on Aug 13, but according to another post, there may be an unscheduled E-night, so ask at your hotel when you check in.