June is a good time to visit, but can still be quite cold in the higher areas. This year, there was still snow in the verges on the B500 in June. Thankfully the weather can be very different betwen the East/West sides of the Black Forest, so when one side has sh*te weather, the other is often warm and sunny. Failing that, the French Elsass/Vogesen is just a short hop.
From the top list, I also forgot "Schau ins Land", which is a former racetrack, now part of the normal road structure. However, it's closed to bikes on Weekends and holidays, so plan for a weekday for this stretch.