Party snack trays default to chips, chocolate and biscuits, but dried fruit holds up just as well on a table for hours without going stale or greasy. Raisins and dates are the two that show up most often, and each earns its spot for different reasons.
Raisins
Raisins work as a stand-in for sugary sweets because the sweetness is already built in — no added sugar needed. Despite the small size, raisins are very nutritious: they carry potassium, iron, B vitamins and a fair amount of fibre for something that fits in a spoon. A few things worth knowing before you put out a bowl:

What the fibre actually does
The fibre in raisins moves food through the digestive system a bit faster than most snack foods do, which is part of why a handful can settle an unsettled stomach for some people. It also means eating a large amount at once can have the opposite effect — bloating rather than comfort — so a small handful, not a full cup, is the right serving for a party bowl.
Iron content, without the overclaim
Raisins carry more iron than most dried snacks, useful as part of a varied diet, though a handful of raisins isn't a substitute for medical treatment for anyone diagnosed with low iron — that's a conversation for a doctor, not a snack tray.
Dates as the other option
Where raisins are small and sweet in short bursts, dates are bigger, chewier, and filling enough that two or three can replace a full snack rather than a handful. Both keep for weeks at room temperature, which is the real reason either one beats fresh fruit on a party table that sits out for a few hours.
For a fibre-rich pick either way, buahkurma.com carries both raisins and a range of whole dates.