I’ve got a fair amount of experience with ASE. I go there every couple months in my ‘C. It’s a beautiful trip.
My parameters:
1) Severe clear. I have the luxury of living in the front-range and can pick/choose which days to go. I realize coming from elsewhere you may not have this flexibility so, I would say 8NM vis minimum. Safety aside, it’s such a pretty trip, why waste it on a hazy day?
2) Light winds aloft en route. My max is 30kts at mountain tops. Look at both the 12K and 15K charts. If either depict winds above 30kts I would stay on the ground. If this is your first time I would say a more conservitve maximum should be 20kts. The mountain wave is no joke in a small plane. Crossing the divide @30kts i’ve experienced severe turbulance, +/- 1,500 ft/min on the VSI, gone zero g, and had some scared passengers.
That’s about it. You really don’t need a high performance aircraft if you stick by those rules. I would whole heartedly advise against going IMC. That’s when you have to worry about climb performance, icing, and unseen terrain.
From the Denver area I recommend BJC RLG SXW LINDZ KASE. Along that route you don’t have to go all that high. Radar coverage is usually available @ FL120. I only pop up to 13K to cross the divide @ Corona Pass, then drop back down.
Check the weather at Berthoud Pass (K0CO) before going. That’s a great station to confirm wind, ceiling, and visibility at the divide. Approaching Aspen give Sunlight Mountain a listen on 126.075.
On busy days expect to be routed over Snowmass Village and overfly the airport for a mid-field entry. I usually recieve the option for 15/33. When departing 33 ask to fly down-valley to the NW. That will give you plenty of time to climb to altitude.