I send letters - particularly to my granddaughter (7) who writes back. I like to use nice writing paper.
However, my handwriting is awful - it always was - and I write my letters on the computer. I spend a lot of time choosing a nice font (although for the DGD it is usually a clear sans serif as she is not a practised reader yet.) I format the page carefully, using colours and adding little illustrations.
For letters to others, which often include photos, I use plain white A4 printer paper so as not to distort the colours of the photos. But here, too, I choose fonts and colours carefully and look at the print preview several times before actually printing out.
To older relatives and for birthdays, special occasions, or just short notes, I use notelets, of which I have a huge collection. I have to adjust the paper format to odd sizes so that the text fits on the page, but again, I format with care and make it as attractive as possible. I did my secretarial training in the 1970s and we learnt a lot about how to arrange things on a page. The computer has made it all so much easier, as has the standardisation to A4 and A5 sizes. (We learnt on foolscap and quarto, but also A4)
After looking at my Christmas cards, which I did by hand this year, I think it is only polite and respectful to use the computer and print letters, notes and greetings cards in such a way that the recipients can read them. To be honest, I was quite ashamed of my handwriting on my Christmas cards.
As I said, most people I am writing to are either very young or quite old and I want to make it as pleasant for them as possible to read what I've written.