I am a firm believer in paper invitations. Yes, Evites are convenient and perfect for say, a book club or a committee meeting. But if you are cleaning the house, making special food and having a party (no matter how small) I think you should send something that is refrigerator-worthy.
We are hosting a potluck dinner for fourteen this December. Our group had to "iron out" a good date via email, so they know the day they are coming over and why. But I won't be happy until this is in their mailbox. Something that says I'm excited that they are coming for dinner and have already starting planning.
Honor your parties by sending real invitations. It will make your guests feel special and be a wonderful visual cue for the fun times ahead.