Here are some of them and I hope they are helpful too. Let's see.
Little Red Riding Hood and The WolfYou can dress as little gentle and naive girl in red and big scary Wolf. And if you are looking for funny idea - how about changing the roles and lady can be the wolf and man Little Red Riding hood?
Image by sparr0, CC BY-SA 2.0, Flickr
Mickey and Minny MouseThey are Disney classics and they look really cute couple. What do you think?
Costumes from the seventies - Hippies or somethingThis one is easy one and you can buy the basic costume and add few accessories you already have at home or make them like necklaces, bracelets, scarfs, headband so so on from the seventies.
Image by storyvillegirl, CC BY-SA 2.0, Flickr
ClownsIf you like jokes and funny stuff you can go out as a clowns. You can be happy or sad clown or each can be different as long as you have colorful outfits. You can even get a scary clown costume - but don't scare too many kids.
Superman and SupergirlDo you like Superheroes? How about the longest known and the most popular one - Superman and his cousin? The Man of Steel movie was big hit this summer and so will be your new costumes.
Image by Digital_Rampage, CC BY 2.0, Flickr
Princess and PrinceIf you want to be royalty this Halloween there are so many beautiful gowns for the princess and so many nitt outfits for the prince. You can choose between Disney Princess as a cute one or Zombie princess on the other side as a dark one. Which one will you choose?
Cards - Queen of Hearts and King of Hearts costumeThese costumes look fantastic. They are colorful and chic. They can be great alone too but in a pair they are unbeatable. Are you interested in winning a best costume competition this year?
PiratesMy last suggestion for couple costumes is Pirate costumes. You can wear matching attire or completely different ones, for instance lady can be sexy pirate and man can be scary pirate with just one eye. And don't forget the accessories like the sword, eye patches, pirate hat and/or bandana, maps, golden coins, telescope, compass...
And of course have a lot of fun.