So I just have to wonder - because I really don't know - what are appropriate expectations for kids regarding time? For instance, it makes sense that a teenager should be able to get themselves somewhere on time. I can see that ability developing in my almost-thirteen-year-old. She is starting to remember where she needs to be, and when, and make sure that I get her there. But not always. On the other hand, my ten year old is still very much dependent on me saying that it's time to get ready to go to _________. However, she can be ready in a decent amount of time. If I say to be ready to leave the house in five minutes, she will be ready.
I am not sure what sorts of time issues you feel your children are failing in. Are they having a hard time staying focused on the task at hand, getting distracted, and not finishing in a reasonable amount of time? That sounds EXACTLY like my son, who is 8. He manages to keep from getting distracted if it's something that he really wants to do (or has a visible reward attached - such as if we hurry and get these errands run we'll have time to stop at the park afterwards). But he isn't managing time himself.
Developmentally, I'm not really sure what to expect from kids. Rafe is teaching 5th graders, so his expectations would be different than mine would be for my 2nd/3rd grader. But I'm not sure exactly what those would be.
Or, are you just talking about school and not about other areas of life? The person who introduced me to homeschooling used to just put her kids' weekly work in little boxes and they managed their own time. Having 20 worksheets to do on Friday was a really quick lesson about the benefits of doing a little bit every day. I guess it worked for her. I never really asked her. Managing time and studies sounds like a very mature ability. I don't know about your kids, but my son is still just getting comfortable with telling time - much less gauging it.
Regarding virtues: I just got a book I requested through PaperBackSwap called "365 Manners Kids Should Know". I am going through a couple of them every week. It's laid out in an interesting format - one lesson per day - for the parent - on a manner they should teach their child. So far I like it. I had though to actually do one lesson per day with my kids, but I think they need time to practice each one and the opportunity to get enough practice in doesn't always arise - plus I only want to be harping on one thing at a time. ;-) We started with how to greet people, particularly adults (smile, make eye-contact, shake their hand, and use their name - Mr. or Mrs. for anyone over 18).
We use the Eyres book for FHE sometimes. We're also going through "For Strength of Youth" for our Sunday night Gospel study with the older kids. I like President Hinckley's book as a devotional idea. I'll have to go find it - it's on those bookshelves somewhere!
One last thing. The other day I did a totally random, must have been inspired, devotional about scripture study. Usually in the morning we sing a bunch of primary songs and hymns, then read a scripture or talk about a picture in the GAK (trying to keep it geared towards the little ones). That day I decided to talk about the importance of studying scriptures. I likened scriptures to salad, and other books to dessert. If we eat/read nothing but dessert - it might taste good for awhile but over the long-run it's not really that good for us. We should eat our salad first and make sure we're getting the important nutrients before moving on to dessert. I challenged the kids to eat their salad every day before moving on to dessert. My kids actually like salad, (literally), so this was an okay metaphor for them. If your kids don't like salad it might not work. ;-) It's been really helpful - especially when we're helping by reminding them. Saying "don't forget your salad" sounds so much nicer than "you better read your scriptures"!! And, it's been a joy to stumble across my kids with their scriptures pulled out as soon as family work is done.