Hey L.Jean... I think 25 to 30 is fine for maintenance, with a long run every other week. That is however with the idea that you are running a solid year before you PLAN your first marathon. With that kind of base you can get up for a marathon in three, preferably four months or 12 to 16 weeks. Also depends on if you plan to just finish your marathon or are planning to do it fast...if fast is in the equation...you'll need more time.

Good advice from Anton. I usually do an off season long run of 12-14 miles every other week. Nothing fast, just nice and easy. It makes the transition back into a training plan easier mentally and physically.

After doing my first 3 marathons, I was tired of dropping all the way down in milage and then building all the way back up. In my non-marathon seasons, I typically try to run around a 10 mile run 2 weekends per month a 12-13 one weekend, and then take an easy weekend the other one. I tend to keep 30-50 miles per week while doing this, but I'm a runner first, triathlete second and am used to the milage. I would say to keep a 10 mile long run consistent, you will probably be wanting to build up, but not much higher than, to a base of 30 miles a week and keep that consistent as well.