Shopping from Wheel is a good answer. I've got two more from Wheel:
Ditching "Buy a Vowel" early on was a good move. (Why did they even have it if you could buy a vowel at your discretion anyway?)
I also think the Toss-Ups were a great addition. They add 3 more puzzles per show, and they distribute the control a little more evenly. Previously, it was red-yellow-blue-red. This meant that red had a slight advantage by getting to start two rounds, and often yellow as well. And even then, sixth rounds were rare.
Granted, the Prize Puzzle often imbalances things unless someone gets lucky on $3,500 or nabs the $10,000 mystery prize, but one problem at a time.