From outside London wish to see some big highlights like Hampton court, never castle,etc. recommend the ones doable from the standpoint of travel by bus or train? Thanks
Hampton Court is easy from London, but it depends where "outside London" you end up at. Hever Castle is a one mile walk from Hever Station, easy to reach from London.
Leeds Castle is easiest on a Saturday when bus 510 runs into the grounds from Ashford railway station (Kent).
If you're thinking stately homes specifically, I'd recommend Hatfield House - its a very easy train trip of just under an hour from London, and the public entry is right opposite the station.
the problem is that you haven't settled on your one hour radius from London base.
Most of the train lines are London-centric and different lines use different stations spread around the Circle Line so getting you a list of top buildings convenient to your train line is difficult.
If part of the reason for being an hour train ride from London is to save money you may well find that you eat up most or all of those savings plus eating up time plus putting up with crowded rush hour trains.
Because we don't have a good idea of your goals, wishes and desires it is hard to hit the target accurately.