I went to Marunuma Kogen 3 days in the 2009-2010 season. The first day was the last Saturday in November, when they only had 3 courses open (Yellow, Violet and Cobalt). While the snow was mostly artificial, it was not bad quality, and it was a nice sunny day. The line for the bottom lift was horrendous, but once we got up it we stuck to the upper lifts and didn't have much problem with lines.
Nasu Onsen Family ski area is a place to teach your little kid how to do the snowplow and ride a chair lift, while getting your ski legs back after a decade(s)-long hiatus. It doesn't pretend to be more than that (just look at the name), and it is perfect for that.
Not too expensive, reasonable rentals, and small enough that nobody can get lost from view for long.
Finally made it to Hunter Mountain near the end of their season, after buying discount tickets pre-season. It had snowed a couple days prior, but the day we went was sunny and warm, 10 degrees or so. Early morning was wet packed powder at the top, becoming shave ice at the bottom, but by lunch-time it was varying grades of shave ice from top to bottom. Solid spring skiing.
The views from the top were nice, and it was a pleasant
A very nice little place Adatara Kogen turned out to be. Compact, but with plenty of trails of different types packed into the space, so lots of variety. Highlights include the ungroomed upper Andromeda course, with knee-high powder "moguls" (for freshies, pay 1,000 yen for first tracks in the morning), the Cassiopeia course which consists of a switchback track with powdery steeps between the straightaways, a pole bahn, a mogul bahn (but too early in the season, apparently --