About the only things within an hour of Boulder are Eldora, Echo Mtn (new resort, mostly terrain park), Loveland, and maybe Winter Park. Open that up to 2 hours and you add Keystone, Breck, A-basin, and Copper. I think of that latter group as being a lot better than the former.
You can get the expected closing dates of all the CO ski resorts here: http://www.coloradoski.com/snow/index.cfm
The backcountry season will be just getting started in mid-April and that opens up a LOT more options. BUT! Please don't head off into the BC without the proper training and equipment and/or a guide. CO snow is really good at killing people.
Lemme know when you're coming out and if you want more beta.