The biggest cause of what we used to call supplemental troubles has historically been low PR. But in some borderline cases, the url can often be brought into showing regularly in search results by having a unique and page specific title and meta description. These are the two areas that get "top level" Google tagging, even for backwater urls.

You may have read posts where people say they can't be found for "exact quoted text on the page". Often that problem can stem from a lack of truly precision tagging on Google's back end. You want to avoid a blurry top level "identity" for the url, especially poor titles, meta descriptions, internal anchor text.

I'd find a way to change up the titles. For example, try to front load the title with the most important keywords FOR THAT PAGE - "Activity in Complete Location Name" or even add another modifier for that internal page. And definitely nail down a good, unique meta description.

Front loading the most differntiable keywords also help visitors to identify pages by being visible in the tabs when they have many pages open at the same time.

No guarantees, of course, but it's a worthwhile experiment to try. Still, the best cure for the supplemental blues is more PR.