Real runner feedback on course feel, crowd support, aid stations, and logistics (parking, hotels, restaurants).
I just did the 2018 marathon and my bride walked the 5 mile event. We liked the lovely, well-marked course; easy entry and packet pickup; casual, low-key, fun atmosphere; responsiveness of organizers to email inquiries; friendly people working the event; and 0830 start.
Packets didn't include information about the course or schedule, so read everything on the web site or ask questions when you pick up your packets. There are few flat stretches on the course, but most of the inclines are either gentle or short. With a start at over 8000 feet and elevation gain the first half of each of 2 loops, I think it even wiser than usual to conserve energy until you're 3/4 done. It would be very easy to overdo on the first descent.
Staying in downtown Vail is a good choice. Prices during off season are not much more than outlying areas. We had a very nice stay at Sitzmark Inn. We could see the start/finish from our balcony, and the post-race food and awards area was just around the corner.
Hotels next to start and finish line, nice course with great deal run on paved greenway, easy package pick up, nice post race food, aid stations were plentiful, very small group of runners
Lonely on second lap of 13 miles, altitude will slow you down if you are not adjusted to it, two loops with elevation gains but nothing drastic.
It could not be easier to get to start/finish line if you stay downtown. You can step out of your hotel door 5 minutes before the start of the race.