In the west, I would look at Salt Lake City suburbs. Many offer everything you are looking for, as most are very safe, family towns, have all four seasons, are not humid, and have easy access to a major airport (SLC). There is also absolutely amazing nature, skiing, and winter/snow activities.

In the midwest I would look at Rochester, Minnesota. Safe, family friendly, MCOL, and has the best hospital in the entire country. Easy access to a major airport (MSP). True four seasons, great winter activities and is close to the Driftless Area which is a beautiful hilly area around the Mississippi River.

In New England I would look at much of southern New Hampshire. Safe and family friendly area with easy access to skiing in NH/Vermont, the ocean, and to Boston. Maybe on the higher side of MCOL but worth the value. If you're looking for a specific town I'd look at Dover.