The best options are probably practical things the couple will actually use. Good quality towels don't cost much but don't look cheap either. Nice bedding, pillows, or stuff like that is always welcome - people just constantly need new things. Or a beautiful wooden cutting board, good kitchen knives, a high-quality pan... those things last forever and aren't kitschy.
If you want something more personal, you can also make something yourself. A homemade gift in a nice box looks really thoughtful and costs almost nothing. Or you give them a voucher for a shared experience - an overnight stay at a nearby hotel, a dinner together, a wellness weekend. It doesn't have to be expensive, but it often feels more valuable than some random object.
Honey, high-quality oils, nice candles, or cosmetics from a good brand are also solid options. And if you're really unsure: casually ask the family what the couple is hoping for. A lot of them hand out a wish list anyway. What matters most is that you show up and congratulate them - that counts for much more than the price of the gift.