I think there's some value in doing one long (30ish miles) run at some point in your schedule because it's a good opportunity to spend time on your feet and to practice the other aspects of a long days running such as planning an eating strategy and hydration and carrying a race pack etc but generally I'd probably stick to a couple of 20 milers as the longest runs in training.
I know what you mean about family commitments, I sometimes look on jealously at people who seem to have unlimited time to spend in the hills every week when I'm plodding the long way to work on a rainy morning but I guess running and life balance are vitally important too
I've been struggling to find a decent pack that doesn't get on my nerves during long runs and I'm looking at lightweight race vest type ones and ideally I'd like something that allows me to carry two bottles on the front straps (not bothered about a bladder) and only really need space in a pack for a jacket and some food so a small pack would be fine.
Trouble I seem to have is that the couple of Salomon packs I've tried so far (XA10+3 and Agile 17) seem to ride quite high up my back when I do up the straps as I'm 6'1" and in the case of the Agile 17, it's basically impossible to reach the side pockets so I want something front mounted and really minimal as I now run with a handheld bottle as well.
I don't know if other taller runners have this problem with packs riding high or if it's just me but it's really annoying having to take off a pack just to access side pockets. The only way it's low enough is to loosen the straps but then it's too loose so I figure a pack that's more like a waistcoat/vest might be a better bet.