You're welcome 🙂
You could also simply copy the iPhoto Library from your wife's MacBook Air to the iMac.
That would have the advantage, that the transfer would be lossless. If you export only the edited versions, the edits will be burned in and you cannot undo them on the iMac. Transferring the iPhoto Library would save the originals as well as the edits and metadata, all albums, etc.
And if you invest into iPhoto Library Manager you can merge the the events with the cruise pictures into your main library on your iMac. That is essentially what I am doing when returning from a trip with a new library full of edited vacation photos on my MacBook Pro. I transfer the library to the Mac with the main photo library and merge the new library into the main library.
iPhoto cannot merge libraries, but iPhoto Library Manager can. But you need the full paid version. Fat Cat Software – iPhoto Library Manager