My first thought was not a letter of the alphabet but a letter in the post. I absolutely love them and I hope that there will never come a point where I have to stop.
I was then thinking of a letter... P came to mind for pen and paper but then I started thinking snail mail, stationery, sweets, sandwiches, stamps..... and my name begins with an S so that kind of outweighted the P... still every stamp needs a price and luckily we work with pennies/pence. I'd love mail 7 days a week but that's only wishful thinking!
Do you have a favourite Letter?