Update: I forgot about one possible thing. There is a bulk edit UI option, but it isn't something that can be easily accessed.

This is tied to a query-updateQueryRows.view page to which you could wire up a button in your grid view via XML Metadata to do a bulk selection.

This isn't all that different than the API update, but does require some more experience with using the LABKEY.ActionURL.buildURL function:

https://www.labkey.org/Documentation/wiki-page.view?name=url

 Also, the UI itself will look a little unusual since it will show what appears to be empty fields if information is different between various rows.

Regards,

Jon