We bought our very good friend a bouquet of flowers a month for her 70th birthday year..delivered by a favourite florist. Repeated that gift for my SiLs 80th. It is nice as each month I get a photo of the bouquet and a catch up of how she is!
You can also organise something similar for cheese lovers. A cheese selection every month/two months etc for the year. We did that for the husband of our friend who got the flowers!
For my DH I have bought experiences; balloon ride etc. Also booked us in for a Michelin Star meal at Tom Kerridge's place for his 65th.
Otherwise it is similar to other ideas: Plants/trees, subscriptions, Spa days, 'experiences' or vouchers for a hotel (e.g , Mr & Mrs Smith, Hotel du Vin etc)
My (not a special) b'day tomorrow...let's see what my family think of!!