Originally Posted by GoBucks

You absolutely must go to Rocky Mountain National Park. The scenery is absolutely eye-popping. Unfortunately Trail Ridge Road probably won't be open all the way through yet, but the trade-off is that the crowds won't be ridiculous. You can still get part-way up Trail Ridge Road and get a taste of the park. Bear Lake is accessible year-round as well.

I live near Nederland and agree that it's worth the drive from Boulder as well. Boulder Falls is about halfway up the canyon and is a nice stop. There isn't much in Nederland itself though, so you won't need more than an afternoon.