W5 was around when I was a kid, and I remember my grandparents taking me and I loved it and the same can be said for my nieces and nephew (ages 6,8 & 6)! Every time they visit there are calls to go to W5 and it never gots old for them (of the adults)
Over 4 floors there are age specific areas for the kids to explore and places for adults to sit. It is educational as well which makes it even better! As you come in there are things to keep the kids entertained from the very beginning and then you can proceed up the musical stairs! The youngest play are has attractions such as a play Tescos, a play Mini, a house they can build onto and a water ball area (aprons provided)
The next one up is for the middle ranges (which my 8yo niece is into now but the 6's can still definitely enjoy) with a variety of scientific and fun things to do like mechano, tug of war, loading cargo ships with cranes ect.
The top floor is for older kids but the young ones will definitely want a play, this is alot of audio visual and interactive screens as well as weather presenting and clever camera/light tricks!!
Don't want to give it all away but there are literally hundreds of things to do and will always occupy a rainy (or sunny) day. 3 hours can cover it and if you get there at opening there shouldnt be much of a queue (Avoid if possible of school holidays or when school trips are likely to arrive)
The only downside is the cost but it is well worth it and there are family tickets available, and annual passes! Year round there are also different exhibitions so check the website!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.