I went to Aspen and back, took Independence Pass both directions. Charged to 90% (235 rated) at Silverthorne, got to Aspen with about 150 miles rated. The trip back to Arvada would have left me with 3% according to the energy page, so I took a 10 minute charge at Silverthorne on the way back and got a drink at Chipotle. Glad I did, there was bumper-to-bumper from the tunnel almost to Idaho Springs (for no good reason), I would have burned the last 3% just running the air conditioner.
If you just want to do it one way, go Independence Pass to Aspen, then down the valley to Glenwood SC. There's only about 15 minutes difference to Aspen between the Independence route and the Vail route.