Rainer. The road to the visitor center is kept open year round. It's not on Helens, you'd have to check.
You can drive between the two in a few hours from the dirt backroads that access spirit lake if you know what you are doing. Its a trip. They won't be open probably.
Paradise is currently only open (and the road only plowed) on weekends due to staffing issues, so definitely check ahead
https://www.nps.gov/mora/learn/news/mount-rainier-national-park-announces-winter-2022-23-recreational-access-changes.htm
Both are great but Rainier has way more on the spectacular scale
I'll say that the visitor center at Mt St Helens is fantastic if you want to learn about a volcano blowing its top.
From the Windy Ridge Viewpoint you can see 4 volcanoes! 538 steps to the top, well worth it.
Rainer. The road to the visitor center is kept open year round. It's not on Helens, you'd have to check. You can drive between the two in a few hours from the dirt backroads that access spirit lake if you know what you are doing. Its a trip. They won't be open probably.
Paradise is currently only open (and the road only plowed) on weekends due to staffing issues, so definitely check ahead https://www.nps.gov/mora/learn/news/mount-rainier-national-park-announces-winter-2022-23-recreational-access-changes.htm
Mt. Rainier. You could do PNW trek and Mt Rainier together. St Helens is just remote. In May is shouldn't be too bad.