20k + miles is fairly common for me.

Here are some of the longer (distances from GCM) sequences I've flown - excluding those under 25k miles (which thus excludes the around the world in under 60 hours).

39864 miles flown including inaugural worlds longest flight each way with some other FTers and followed up by 7 crazy days

35529 flown miles

32985 flown miles - first part of this report

29470 miles flown - a medley of SQ new F, new J and old J

28240 miles flown - part of oneworld revolutions

28050 miles flown as part of big Do Dos month of madness

27443 miles flown

27223 miles flown

146k flown miles in 29 days which had maximum spells without leaving the airport of 25k, 23k, 23k and 20k - all within the same month (and maximum time out of airports of half a day).