How about West Sussex?
It would take about 90 mins to get there. You could base yourself in Chichester or maybe Midhurst (I slightly prefer Chichester) and from there you have Arundel, Goodwood, Fishbourne Palace, beaches and harbour, South Downs villages, pretty Chichester itself, the Weald and Downland Museum and even Portsmouth Maritime museum and harbour is within reach.

Leeds or Hever Castle in Kent and Hampton Court.

Weekend Trips I always recommend for our visitors:
Windsor Castle
Bath
Canterbury (our personal favourite) - the church is amazing and the village/town is very cute
Stonehenge/The Cotswolds (but only if they have time and are really interested, as can be a journey to get to and not that awe inspiring once there)
For a little more time a trip to Devon or The Lake District.

Have fun!

For London it has the be the "Eye" and drinks at Windows at dusk on Park Lane, beautiful. I'd also do The Tower of London and the City on a Saturday afternoon for a walking tour as some of that is fascinating.

Outside London it really depends how far...

Cambridge and Oxford are always lovely, Stonehenge is a pain to get to but quite awe inspiring when you're there. If you hire a car you can do Stonehenge on the way to Bath and that's a lovely drive and Bath itself is beautiful and well worth an overnight stay.

I'll post if I think of anything else!

Hello - My parents are visiting us from our home country and are hoping to do a little sightseeing across the UK, while here. Preferably short weekend trips.

Any suggestions? Castles to visit? Other sightseeing? - - welcome hotel ideas too!

Thanks!