The north side of canyons usually gets enough sun to melt after a few days. If you find a place with a ton of cracks on the front range please report back / DM me because I'm always on the hunt...
Quarry wall at NTM is a good winter training ground for cracks.
South Platte is great for this criteria - hard to give specific recommendations without knowing more about your preferred styles and abilities but Turkey rocks is the classic winter crack climbing area, as well as cathedral spires until the raptor nesting closures take effect again, Buffalo creek is crawling with crack boulders, there’s a ton of sport climbing around (though most is slab/technical face) - Staunton being the spot for well protected, more featured hard sport climbing in the region. If you’re really feeling yourself Tyler Casey did a great job with the crystal fortress and there’s a bunch of rock to sample in the thunder ridge region as well.
The Platte is generally very exposed due to enormous forest fires that hit the region and being a pattern of granite domes rather than steep canyons - as a result, you can typically expect most crags to be snow free a day or two after snowfall and warm on all but the coldest and windiest days.