THe weekend LSR's are very important, dave, and if you're up to 18 miles, that's looking good, ideally you want to get in 5 x 20 milers, and you don't want to do them all on sucessive weekends, so you can alternate them with slightly shorter lsr's which contain some marathon pace running. For the midweek mileage- that's a great bonus- Pfizinger & Dougles suggests medium long runs during the week- they go up to 12 miles. These are done at long run pace, occaisionally with a block of tempo pace in them. The problem is that you need to get the occaisional very long run in, or you'll struggle in the latter stages. This will give you quite a jump in mileage, I guess, so do a lot of it slow, and hopefully you won't damage yourself.
i'm going to be adding an out-&-back of 11 miles each way, and a partial out and back of 6 miles each way, now that there's more day light- but I'll still need to do a proprer LSR, too , so you're not alone.
