We've been Winnie the Witch mad recently, mainly reading Winnie's New Computer - because that is the only Winnie book we have! Although we've had quite a few out from the library in the last few months, Winnie in Winter being a favourite, too.
I think Rosie particularly likes the computer one because she feels sorry for Wilbur being shut out in the rain and being turned blue and then invisible. It's nicely done and thankfully fun to read (I think it might be nearing about 50 times now, I'm available for recitals!).
I think the Winnie books are charming and there is enough extra detail in the illustrations to bear rereading them again and again. The duo of Winnie and Wilbur is great fun too, although Wilbur always seems to bear the brunt of Winnie's crazy plans.