A good way to start the day are at the National Gallery or the National Portrait Gallery in Trafalgar Square (or both.)
As well as blockbuster exhibitions (which you may like to avoid if you hate crowds) the paintings the National Gallery hold include those by CÚzanne and Gainsborough, Rembrandt and Van Gogh. Here's a list of their 30 must-see paintings.
My favourite paintings in the National Portrait Gallery are those of Elizabeth I and Henry VIII, but the Gallery's collection includes portraits of writers, artists and assorted very rich British people.
St Martin in the Fields Crypt Cafe www2.stmartin-in-the-fields.org
After your culture fix, try a bit more with lunch and a concert in St Martin in the Fields. There's a cafe in the crypt of this beautiful old church (the first reference to a church on this site was in 1222) and could be soup and sandwiches, stew or fish and chips. The concerts, which are held down in these atmospheric old chambers may feature a pianist, choir or a string quartet.
After lunch, wander over to Covent Garden - it's not far. This old fruit and veg market is still a beautiful old building, and there's usually something happening in the area - whether tightrope walkers, opera singers or street dancers.
It's always a busy area, but there is a quiet place to have a sit-down and a cup of coffee - the grounds of the actor's church (otherwise known as St Paul's). This church, along with Covent Garden market, was designed by renowned architect Inigo Jones and you'll see memorials to Charlie Chaplin, Boris Karloff and Vivien Leigh among many others within. There are also extremely handy to know of public toilets just outside if you happen to have had a rather large latte.
Don't leave Covent Garden without visiting the London Transport Museum. This museum isn't just about buses and trains (interesting though they may be) - it's about the growth of the great city of London. The expansion of the tube network drove the growth in population to the size that it is today, and it's fascinating to learn just how that happened.
End the day in one of the many pubs in the area, or go to the theatre, your choice. Pub-wise I would heartily recommend Champagne Charlies in Villiers Street, near Charing Cross Station, or have a posh cocktail at Upstairs at Rules.
If you are in the mood for a play or a musical after that fun-filled day, have a look at Theatre Monkey) for tickets as well as advice on which seats to go for - they have guides to the best value ones to go for in all of the main London theatres.