Style poll

options.rb

# Option 1
info = if publication
  "Title: #{ publication.title } (ID: #{ publication.id })"
else
  'N/A'
end

# Option 2
info = case publication
when Publication then puts "Title: #{ publication.title } (ID: #{ publication.id })"
when nil         then puts 'N/A'
end

for option 2 I also find the indentation a bit weird. Maybe if the when statements where indented or even aligned with the case.

def publication_caption(publication)
  return 'N/A' if publication.nil?
  "Title: #{ publication.title } (ID: #{ publication.id })"
end

info = pubication_caption(publication)

Actually long term in such cases I would use the null object pattern (see https://github.com/avdi/naught) and define #to_s on both NullPublication and Publication.

From your options however, the first one seems a lot more readable, if the only case you need to address is NIlClass.