My training volume increased ever so slightly last week with my weekday runs going from a 6 mile to 8 mile average and my long run on Sunday was extended by 2.5 miles to 11 miles. At the moment I'm still planning next year and although I have a fair idea of what i'll be doing it's still too early to start putting my body under too much stress as I much prefer to use this time to build a good foundation on which to get event specific when the time comes.
I've also mapped out a local route that includes quite a few hills and is just over an 8 mile loop starting from my house, I'll run this route once a week with a gradualy increasing pace using the virtual partner on my Garmin.
Knowing how far and how fast to run during the Long Run is determined by how far you'll have to run during your planned event but there is a distance at which you can max out and it's probably not sensible to go beyond that. This distance and pace differs from person to person but I find that if I'm on the go for longer than 4.5 hours I take longer to recover and going for an extra half to 1 hour can cost me a training session or more in the following days. No big deal but if it's close to an important race it can make a big difference.
As a rule if I'm training for a Marathon I run my long run slower than my planned race pace and if I'm training for an Ultra my long run will be at race pace or faster depending on the race distance. If you can't hold a conversation during your long run then chances are it's too fast.