We've been going through a similar situation here. We have a Wii as well, and have really gotten a ton of use out of it over the years, but now it is getting to the point where you can't get new games for it - and like mentioned earlier, not being able to get Disney Infinity 2.0 sort of was the tipping point for our house too. Nothing wrong with it otherwise, still works great and everything, but it might be time for something new. Our daughter really wants a WiiU, and to be honest, we've always sort of been a Nintendo household. I know it isn't as good a system as either the PS4 or XBox, and won't have nearly the game, but honestly with a 7 year old girl we're not necessarily looking at playing games like Halo, Call of Duty, etc. (and I don't have that kind of time anyways).
We are thinking about getting a WiiU for Christmas, but honestly it was the fact that it had been a bit of a failure that was scaring me off. However, I've been reading some articles int he past couple weeks that discusses the WiiU has really picked up in recent months, mainly due to both SuperSmash and the whole Amiibo thing. I know it won't ever meet PS4 levels, but hopefully it will become a healthy enough system to last awhile. I feel like such an old man, because all of these systems (and games for that matter) seem way too expensive to me. I remember when a Nintendo was a $100 dagnabbit.