I don’t know your wife nor do I know enough about easy terrain at Colorado resorts, but I do notice you are going in mid April.
I think besides the actual terrain, the more important consideration is how the easier runs, and especially the return to base runs, hold up in spring.
Steamboat is a perfect example where the bottom part of the mountain gets slushy quickly (low altitude for CO, and West facing), and it is a bit steeper anyway. This leads to the runs turning into piles of slush on a sheet of ice. The same thing is common in other areas. Many beginner skiers (rightly) find this terrifying.
So my recommendation is:
- Find a resort with good late season conditions (high altitude and north facing terrain)*
- Make sure there are north facing, wide, mellow green groomers back to base, or better yet, a downloading option from mid mountain.**
- Get her a lesson. In spring conditions change so much throughout the day that local knowledge about which runs will be in good shape at any given time is worth the money in its own right, let alone the confidence and skills she will gain from the actual lesson.
*Here is a good starting point:
http://bestsnow.net/latesnow.htm and
http://bestsnow.net/fam_ski.htm
** use caltopo.com. Select add item, DEM shading, aspect NW to NE, select ‘add rule’ and it will highlight the north facing terrain. Here is an example from Copper Mountain. Copper certainly seems like one of the best options since the base is high, the mountain generally faces north, and they have good beginner groomers down to the base that are not very heavily used. As well as some nice beginner terrain up high.