Will it be fun to go to Legoland with my family?
My wife and sister-in-law enjoyed our trip to LEGOLand with our sons, everyone enjoyed the models, however not everyone was as keen on the rides, you mileage without kids to share the rides with may be different.

The question then comes down to whether you feel the model world is going to justify the entrance fee, personally I found the UK park to be (comparatively) expensive compared to other theme parks in England.