Victoria or Holborn area from/to LHR, Big Ben, British Museum?

thanks--we are going to take the Tube coming from LHR--I assume it would be safe at 10PM on a Sat night to Victoria (change at Earls, I believe) and then walking a few blocks at 11 PM around Victoria--I assume Victoria area is pretty lively on a Sat night (OK for children)? I thought the Coach would be easiest for Sunday afternoon around 3:30 for a 6:30 flight--not much traffic and easy to just get on a stow luggage--but we could easily do the tube/train also--please advise if assumptions are incorrect. (PS--the walk form Victoria-BB--is it safe on a Sun AM---just not picturesque--or will we be walking past unsavory sorts?

You say you are using the national Express coach between Heathrow and Victoria ??
Last bus from Heathrow is currently 21:40 which you won't make if your flight is on time, so you'll need to use the Underground changing at Hammersmith.
The bus doesn't go to the terminals at Heathrow, the bus station is OK for Terminals 1,2,3 but requires a walk and a train for Terminals 4 and 5.
Big Ben is a 15 minute walk from Victoria and not a great walk either. Big ben to the British Museum is a very nice walk, especially on a Sunday Morning up whitehall past Downing Street, catch the changing of the guards at Horseguards through Trafalgar Square, China Town and the book district to Bloomsbury/British Museum.
It doesn't really matter where you stay in Central London, both Bloomsbury and Victoria are fine - just work with the accommodation that is right for you and plan around that, public transport will take care of all the logistics wherever you are.

On the Underground from Heathrow to Victoria change at Hammersmith or Barons Court. If you change at Earls Court you will have to go up escalators and stairs with luggage, at Hammersmith & Barons Court both trains leave from the same platform.

The National Express bus between Heathrow and Victoria on paper has a maximum weight per bag of 20kg (44lbs), but they don't weigh the bags or anything and most drivers will turn a blind eye - but you only need a jobsworth.

Regards the safety issues raised, you should have no concern - both on the Underground and walking around. There is nothing wrong with the walk from Victoria to Big Ben its just so much blander than the walk from Big Ben to British Museum which has something new and interesting around every corner.

thanks to all--I love the helpline. We all have smaller backpacks and just 3 medium suitcases between 6 of us. All are 20 kg or less, as we have to be under 20 kg for our intra-European flights anyway. ps--how long would the walk form BB to British M take us? 30 minutes? Is there a bus that goes that way(preferably a double decker)--city bus, not a tour bus? or something that gets us in the general area and then we could walk the rest?

For travel from Victoria to the British Museum, the best route is to take a 38. Get off the bus outside St George's Church, Bloomsbury and the Museum is on the opposite side of the block.