Hey there batbike,
I ride by miles and I can get in 30 miles per day easily. The trick for me: commuting! I live about 10-15 miles one way from work (depending on route), so right there I have 20-30 miles in a day. Other tricks: riding during lunch (if you have a long enough lunch to put in a couple of miles) and riding in the morning or evening, especially since the sun is setting later. Hope this helps