I hope someone can give me a little guidance. After combing through the forum for serif combinations with Avenir, I thought I would try a direct request. I am about to embark on the design of a range of reports for a Europrean rail transportation organisation. The reports will be of varying length, the biggest being about 140 (roughly A4) pages long. The reports themselves will be combining full colour imagery, pull out case studies, maps and various charts and graphs. It's a pretty large undertaking all in all and I really want to do a good job.
The organisation makes use of Avenir as their primary face, although I'm actually leaning towards using Avenir Next as it seems to offer more flexibility. However, I'd really like to find a nice serif to pair it with.