I have skied Monarch the last five years. Prior experiences include most Colorado resorts, Deer Valley in Utah, and extensive time at Zermatt and Davos in Switzerland.
Monarch is a mid-sized place, not small but not nearly an Aspen or Vail. All runs end up at the same base location, so most unlikely that family members would get lost. Lodge is ok, bar is cosy.
Nice mix of intermediate and advanced runs, with recent upgrade to beginners area. Good little-kids area. Some runs are consistently groomed, others not (on purpose), or only one side of a run, etc. I think run maintenance is very good.
Lift tickets are a real bargain, with lots of deals available through motels in Salida (15 miles to east on Hwy 50). Also Monarch Lodge, about 5 miles east of Monarch, probably the top place. Buy your tickets in a package with lodging to get best deal.
Equipment rental at Monarch is very reasonable with good quality equipment, including demos. Also towards Salida are three good ski shops. $14 or so per day will get you nicely equipped.
Everyone at Monarch is friendly and helpful - and I mean everyone. Cafeteria workers, lift operators, instructors, clerical, etc, etc.
Oh, and the snow - lots of it. All natural. Some 30ft or so during the season. Typical base by mid december is about 4ft. When Monarch closes in early April it is not unusual for base to still be 6ft or more. Due to high altitude on continental divide (base is about 10,600ft), the snow is consistently dry. Great powder.
If you hate lift lines, go to Monarch. Most times during week absolutely NO ONE in a line, ever. On regular weekends, you might have a couple of people. The worst might be the bottom lift right after lunch where there might be a couple of minute wait, but that is unusual. Even during Christmas and spring break the lines are quite modest, with the worst being in the beginner area and bottom lift. Stay away from those two lifts and you won't have much of a wait. And that's the worst it gets. Some days I wish more people were on the slopes, so Monarch would make more money !!!
As you can tell, I highly recommend Monarch, especially for families. Modest prices, no crowds, friendly people, good snow, reasonably large ski area. Enjoy.