On subject of surprise visits, while they may bring a lot of joy to both parties interested one needs to be prepared for one of two disapointments:
1 / person to be surprised by our visit may be absent
or even worse
2/ we may find him/her in company of somebody we don't know or, horror of horrors, somebody we don't like
Just last week my friend drove 400 km to pay surprise visit on his brother 65th birthday only to find house closed and to be informed by the neighbour he and his wife went for surprise holidays.