Which wii game should we get?

My husband and I just got a Wii for Christmas, so the only things we have are 2 controllers/nunchucks and wii sports. We have a few games we were considering: Endless Ocean, Samba De Amigo, Wii Play, and any of the Mario games. We wanted something fun to play (not mind boggling and difficult) that we could preferrably play together (but we're okay with taking turns). If you were only going to buy one game, what would it be?