I suspect that hotels would prefer items that do not tie up time of high level staff or require lots of time to arrange, although of course this depends on whether the list would be sent to guests well in advance to submit ahead of a deadline versus offering almost impulse items at check in.

Some items that I might appreciate could include branded or seasonal items from the hotel gift shop, treats such as chocolate dipped strawberrries and champagne, high tea, a city tour or seasonal trip in a hotel limo (Christmas lights from the St Regis in Singapore, cherry blossom time from the Westin Tokyo or a Washington DC property), helicopter service, a private trip in a hotel boat perhaps with wine and cheese if allowed by local law, a fancy picnic basket lunch, airport limo transfers especially if combined with VIP meet and great service of some sort to make it special, a scheduled cocktail party with the GM and other hotel guests (some hotels already do this regularly without a charge, although not all hotel guests are necessarily invited), insider stuff like a tour of very special suites in historic properties or a hard hat tour of a new wing or renovation project, a golf or tennis lesson, a cooking lesson, swimming or skiing lessons for kids and/or adults,.....However, these items should not displace normal hotel services such as providing birthday cakes or welcome gifts for elites or regular customers.