Multi-Item Edit v4.3 will allow you to edit most tags (and some additional options) of the selected track(s) in a single floating window using single-edit mode (one selected track) or multi-edit mode, which emulates the pre-iTunes 12 "multiple items" format; that is, a checkbox adjacent to each tag allows you to select which changes are to be applied to the selection's tags.
This latest version adds support for iTunes 12.2 including the new "Loved" (or "Likes", I suppose) rating tag. I removed the "Album Rating" tag setting to make room for "Loved", but "Album Rating" was proving difficult to reliably compute when tracks were from disparate albums. I don't think it will be missed. You'll also be able to edit tags when a selection of tracks contains more than one kind of media.
This update is free for registered users. New users can try it free for 10 days; it's $1.99 thereafter.
More informationincluding videoand download is on this page.