Portals work pretty much the same as a Sub Report or Sub Form in access. In what way didn't that work for you?
Portals are often not the best approach for printing as you can end up with problems where not all the listed trip details are printed unless the portal is large enough to display all the rows without scrolling. You can create a very tall portal and then set it to slide up to reduce unused space.
A better approach is the summary report you said you also didn't have much luck with.
If you base your layout on the details table, you can put the fields from the related parent table in either the header or a sub summary part. Since your detail records are now in the report body, the issues you encounter with portals aren't a factor anymore. This second approach requires that you pull up just the detail records for the desired parent record or records and to then Sort them (espcially if you use a sub summary part) correctly.