We are in London right now and we are deciding between a day trip to either of these castles. Hever is closer by, but I've read some great things about Dover. Which would you choose?

OK -- they are complete apples and oranges. Hever has glorious grounds -- i.e. pretty gardens. Which aren't really an October 'thing'. The castle is OK as castles go but the place has become more of a wedding and corporate venue than historic experience.

Dover castle is humongous and has everything from a Roman lighthouse, to medieval castle, to Victorian barracks to really fascinating WWII tunnels with army hospital and communications headquarters (sort of 'Churchill War Rooms-esque')

There is MUCH more to see and do at Dover. The town of Dover has nothing to recommend it really (parts are a real dump) so just take the train and then catch a taxi up to the castle (it is a steep hill so don't even consider walking). One can spend most of a day exploring the Castle etc. If you have extra time, Deal Castle and Walmer Castle are nearby. Deal is fascinating -- very original and they hand out torches (flashlights) to explore parts. Walmer was originally a defensive castle just like Deal but was converted to a beautiful 'palace' - lots of connections to the Queen Mother being best friends with the owners

That's some great info--Dover it is. Thanks janis.