I like the half-proficiency bonus to non-proficient saves house rule. A +1 to +3 makes a bit of a difference without getting too crazy. For those who don't like it right away, it could kick in at 5th when proficiency bonus first goes up.
So at 1st : +2/+0, at 5th: +3/+1, at 9th: +4/+2, at...