Might be in a minority of one here, but if an established couple have enough money, can afford holidays, and most especially have no kids, I don't think they should expect any presents. Merely attending a wedding can often be quite expensive for many people, what with travel, accommodation, often drinks, maybe having to buy an outfit, etc.
A lot of guests had to travel quite a distance to my dd's wedding 18 months ago - she and my SiL had just bought a slightly bigger house, had a small baby, and were by no means flush, but the invitations still said, 'No presents, just presence.'
Ditto for her cousin's wedding the year before at the same venue.
Some people did give something anyway, esp. close family, cash or vouchers, but it was quite clear that nothing was expected.