We did Welcome Home Wednesdays - it was nothing like the summer block party (or summer on the savanna). At welcome home Wednesdays, it's very low-key: you get a DVC baseball cap, a bag of cracker jacks and lemonade. There's a DVC trivia "game show" that is kinda cute.
The summer parties have a DJ, free facepainting, games, characters, free hats (it was flashing pins at the block party), free mickey ice cream, drinks, popcorn. The block party gave you free admission to PI for the evening (an awesome perk). Summer on the Savanna did not give you PI admission, but there were lots of Disney characters and the really fancy face-painting was free.
We thought the Welcome Home Wednesdays were an okay way to spend a rainy hour - but the block party was the highlight of my kid's trip the year we went.