I worked with the League of Women Voters of Denver for many years and they did a good job of covering all the referendum issues. We studied the issues carefully and took brochures to all the libraries and other places in Denver. From the State office we mailed brochures around the state. I live in Boulder now but if you call or email lwvdenver.org they will help. All Leagues have very little money to work with so I'm not sure how much they are doing but I can assure you that while they are are nonpartisan they are true progressives in the way they decide issues, registering and getting out the vote, and working for fair elections. They believe every vote counts and I'm glad you do too! Coloradopols.com is a good site also and Westword and Denver Weekly may help.
Ideally it would explain the rationales behind the choices, and include candidates and referendum issues from different counties, but I couldn't find anything comprehensive.