Several things help me enjoy D&D more this round than back in the 80s.
Getting the idea that running older D&D is more about making rulings than looking up rules.
Having a over a decade of reenactment and boffer live-action rpg experience which helps me describe and referee combat better which is important considering how abstract D&D combat is.
I simply improved as a referee and know more stuff to make interesting and memorable encounters. Because of the nature of the D&D rules, I do more of my thinking is on the details of the encounter rather than looking stuff up.
The wealth of material to draw on when I am pressed for time is staggering.
Having my house rules in a printed form, the Majestic Wilderlands, has been really helpful. Even you don't want to be a publisher I recommend using Lulu to print up your own collection. Or if you don't have a lot, use the local copy store to make a bound copy.