My husband and I will be in Denver for a conference in a few weeks. We are wondering if it's possible to take day trips/tours to mountains from the city? We would love some suggestions. Thanks.

Sure. A lot will depend on the weather, but there are plenty of options. Some section of the Peak-to-Peak highway is a realy good one. See this map:
http://www.coloradodirectory.com/map...to-Peak-SB.gif

For example, if you did Denver - Boulder - Lyons - Estes - Nederland - Boulder - Denver that would be about 4 hours of drive time in good weather. With stops for meals, photos, short walks, it easily turns into a nice full day trip.

Going up I-70 to Idaho Springs, Georgetown (nice little town) or Summit County is also within day trip range, but I think driving the Peak-to-Peak is more interesting.

Plenty of options! Have a good trip.

Depends by what you mean by trips/tours. The mountains are less than 30 minutes to the west so you can get there easily and quickly but no public transportation. As a resident I am not aware of any organized day trips but I am sure they exist if you google Denver. The easiest thing would be to rent a car for the day.

Shorter trips closer to Denver could be...
You could visit Red Rocks/Morrison, Coors Brewery/Golden (not quite the mountains).
Or go up to Blackhawk/Central City and hit the casinos (and maybe Idaho Springs (Indian hot springs, caves).
Georgetown is scenic, too...will all probably depend on the weather. Could be gorgeous, or...not.

Thanks very much.