For spells: an increased range does not make sense, in my opinion. If we get a bonus, spells that use a ranged attack roll (e.g. ray of frost) will use that at well. But that leaves the question, what do spells get that have a saving throw mechanic? If my wizard casts e.g. Fireball, should there be bonus on spell save DC as well? For me it makes not much sense, but for balance reasons, there should be something like that.
Maybe a bonus to Dex-only ST spells? Cover in 5e works a similar way: in cover you get bonuses to both AC and Dex Saving Throws.
Thus, if we interpret the high ground bonus as actually coming from better ability to see our enemies, then an increase in both attack rolls and Dex-based spell DCs would make sense.
