Legoland was great. This our 3rd visit. It is really a kids place (I wouldn't go without them) but there is loads to do.
It is also a really bad place for queuing. Waiting 30mins plus for a 5 minute ride/attraction is normal. You have decided what you really want to do before you get there I suppose. There is a map on the website and it pays to plan a route as it is quite hilly - you don't want to be going up and down the hills all day.
I wouldn't have gone if it had been as hot as Thursday and I wouldn't go if it was rainy as it is mostly out doors - very little indoors stuff worth doing.
My boys are 5 and 8 (just - nearly 6 and 9) and liked the Pharoahs and Vikings (got soaked) activities best plus Miniland where all the model towns and villages are which is my favourite.
If you have little ones who like Duplo there are lots of water fountains and squirty things in Duploworld which warrant a swimming cossie.
Make sure you book on-line if you go as you get 10% off (would have been £120 for 4 of us at the gate). We used Nectar points and I think you can use Tesco vouchers too. There are other offers around - friends had a 2 for 1 voucher from somewhere. You shouldn't ever have to pay full gate price if you keep an eye open for a deal.
Food and drink also pricey - take a pack lunch! Queues are bad for food too.
Ankles are still aching - I don't think my sandals were sufficiently supportive for an all day trek.
Oh sorry - I seem to have gone on a bit! This probably not the place for a review but it can be a frustrating place if you pay a fortune and the can't see much as you have to spend most of the day queuing, so better to be forewarned I think!
Hope I haven't put you off - if is great fun.