Chris- sounds like you have a good, conservative plan. My comments:
As you increase mileage, don't be afraid to vary your mileage a bit day-to-day. For example, 7 miles one day, 12 the next, etc. But 60 miles/week is a great base, and if you want to do it 10 miles/day, that is fine. For your long run, that is one of the most important things for your marathon, so getting as many 17-22 mile runs is important. And you don't necessarily have to wait till you hit 10 mpd before building your long run- you can start now. You could do something like 6-6-6-6-4-10. Your long run can be up to 30% of your total mileage, so you could do a 16 mile long run once your daily run is 7-8 miles.
To address your questions-
For doubles, they can help once your mileage gets high enough. I don't think it's worth the time to do less than 4-6 miles/run, though, so I wouldn't start doubles until you hit 8+ miles/day. And doing some days of doubles and some of longer runs (i.e. 8-10 miles) is good. Read these posts:
http://fastrunningblog.com/forum/index.php/topic,228.0.htmlhttp://fastrunningblog.com/forum/index.php/topic,793.0.htmlRunning before/after marathon: Everyone has their own tapering philosophy, with general consensus of no more than 3 weeks taper. I've found I run best with about a 10 day taper, slowly reducing miles until my last 3-5 days pre-marathon are pretty easy. You do want to keep running, though- no running will lead to sluggishness and loss of fitness. But everyone is different and you have to learn what works for you. It is better to be rested/healthy than worn down, though. If you are up to 60-70 miles/week before the marathon, you could do a 3 week taper of 55 miles, 40-50 miles, and 20-35 miles pre-marathon, depending how you feel. After the marathon, take some time off if you want. You're much more likely to get injured/sick by running, and have little to gain. It's not uncommon to take 1-2 weeks completely off, or very easy running/crosstraining. You can be back up to full mileage in about 4 weeks.
Good Utah marathons- sure. I'd say all are pretty good. My favorite is Top of Utah, though I don't think any are bad. But I'm also a fan of doing marathons close to home (no travel, cheap, sleep in my own bed, train on the course). Get through your first marathon first, then start looking at others. If I personally travel to a marathon, I make sure it's a great one, like Boston, Maui, etc.
