Also note that "buddy pass" travel is usually, if not always, based on "space available". That means that you are at the very bottom of the standby list. In today's world of full flights / load factors >= 90%, this can mean a lot of waiting in airports. Friends of mine recently used UA buddy passes to fly to SE Asia on *A partner carriers. It took them 4 days to get there and 3 to get back (on paid fares, it is usually 2 days to get there and one very long day to get back).

In the past, non-revs often were given premium class seats, as these did not sell out. These days, J and F are often full, or even if not full, are not given to non-revs (on SE Asian carriers, at least). Other friends have spoken of the glory days of flying UA International F on buddy passes, but I have not heard such tales in the past couple years.

Policies regarding flying on buddy passes and whether they require that the employee be present seem to vary widely among different carriers. The aforementioned friends who went to SE Asia were with the UA employee.