Mount Solitude can be reached from Pitkin , Bighorn and Boulder Creek Valley.
Boulder Creek: accessible via Rock Creek Trailhead - road sees very heavy use by campers and road conditions get worse every year. Normal sedans could still use the road if you take it very slow ( status 2021). There is a short but steep sections midway with very deep potholes, if they get worse you may not be able to make it up without high clearance in the years to come. Many places were you can pull out if you decide that road is too rough, or simply park at the winter parking lot where the rough part of the road starts. This adds 1.7 miles one way to your trip
Access via Gore Creek & Boulder Creek Trail- Boulder Creek Trail is not maintained anymore past Boulder Lake by NFS - trail is now disappearing under tons of fallen trees - so this will be a long and tedious bushwhack. No save descent down from Mount Solitude back to Boulder Creek Valley - scramble North along the ridge via Vista Peak to Usable Pass and bushwhack back down the valley back to Boulder Lake.
Bighorn Creek: no overnight parking is allowed anymore at trailhead - overflow parking at the interstate exit does not allow overnight parking either.
Free overnight parking at Village Center Parking Structure - take East Vail Bus close to trailhead
Access to summit via Climbers's Point or climb over to Boulder Creek Valley via Bergschrund at the most upper part of Bighorn Valley
Pitkin Creek: parking is also limited to 3 hrs
Access to the summit via its Western grassy slopes (basically a walk up) or via Usable Pass and trailless to Mount Solitude's East Face.
You will hike almost entirely within the Eagle's Nest Wilderness - please abide to all wilderness regulations to keep this place wild and pristine