I've made several setting that were magical, but where society had existed starting at a near medieval level for a couple thousand years. Rather than the typical fantasy world solution where there is a fantasy setting that seems to have existed for all time in its current state I assumed that society built up just as fast as it did from the late iron age to the present. The most gifted individuals mentally often went into magical pursuits (that's were the money and the challenge is) so material science suffered leading to limited gains (compounded by the fact that magic can quickly achieve greater results than small incremental improvements is some areas of design). The wealthy, who bankroll the research, sought magic to wage war and look after their health and lineage so military magics and healing (along with fertility) all advanced to closer to modern levels (in my setting healing actually surpassed modern levels for those who could afford it, but with more targeted military magic due to the need to fight dragons specifically). The end result was a society that looked fairly late medieval in its construction, but with a number of the trappings of a more modern world (higher life spans, more belongings for the poor due in part to more commerce generated by magic travel and goods, more destructive warfare, and more mobility).