After work/before work or weekend rides ?
My weekday before /after work rides all take 7 mi of riding "bike path/urban ST" round trip just to get to my trailhead. From there, the skies the limit. If I'm lazy, I'll just do 3-4 loops on the lowest easy XC trail, 4 mi a loop. If I'm ambitious, I'll throw in 15 mi of moderate technical ST with some decent climbing instead of the easy loop. So... my normal daily workday ride is between 19-23 mi.
Weekends are a totally different story. I usually shoot for a 4-6 hr ride, mileage varies. One weekend it can be a never ending hike a bike uphill, for a 1 hr DH. Other times I like to go explore unreported trails that I found on a topo. Most times I'll hit up my favorite trails . Other times when I'm "lazy", I'll just do an easy XC of 35-45 mi..