When I title the books in the metadata, I actually use the series name and placement first, then the actually book title.
As an example, I'd re-title J.D. Robb's "Naked in Death" as "Eve Dallas 01 - Naked in Death".
Then when I sort by title, they're all together.
I'll admit, I started doing that when my ebook reader was the eBookwise. No collections on that. But I'm used to it now and I like it.
If I was starting over, I might just try to get the collections cleaned up and leave the titles. There are some book series that all I can see in the TOC is the series name and placement...it's too long to read the book title too.