How do y'all handle multi select parameters on a script? Currently I use a comma delimited list, but I'm hoping there is a better solution.

Sometimes that comma-separated list is the best way. In some cases, though, it makes sense to have a saved search as your parameter and plug in your multiple values in the filter of your search. In other cases, just defining a custom record type that has a multiple select field on it, then selecting an instance of that record will work best.