I have done one- 102 miles to be exact. It was the Outlaw Trail Century in Round Rock, Texas last fall. The ride was poorly supported, but I didn't have problems until mile 96 or so.

DH and I have done the Houston to Austin MS150 twice and day one is close to a century. This year it was 95 miles and I wanted to head 2.5 miles down the road to get the century. DH would have none of that nonsense. That leg of the MS150 is mostly flat so I felt great by La Grange. Day two is 80 miles of hills, hills and more hills.

I prefer 60-75 miles myself. Somewhere after 80 miles I begin wondering if I hate myself? We will do more centuries, probably one this fall, but I like the Metrics better.