Lots of snow still in March. Bring skis or snowshoes. ;)
If you want to hike, Roxborough State Park is nearby and offers some good early Spring hikes.
Interesting Rock formations, cool little hikes, and a nice way to stretch your legs without major altitude considerations.
A trip I did there in 2010 to scout out a CT alternate start:
Roxboro State Park
If you are willing to drive a bit (less than hour - depending where you are in Denver), the Boulder Open Space and Mountain Park has a LOT of hiking. From gentle strolls at the edge of plains to hiking 8500' peaks in town.
Some good hiking ideas:
So, pretty much the foothills for day hikes. But, they are good hikes in their own right!
If you want to backpack, this loop is interesting in a chill, relaxing way:
Twin Owls Loopt
Could be a nice, moderate backpacking trip without too much altitude to worry about.
It is in Rocky Mtn NP, so not too far of a drive.
Naturally, you can car camp at RMNP and do day hikes from the area as well.
If you need some more specific ideas, please ping me!