I preferred the Winner's Board to the Shopping format as they were presented. I echo the sentiment of those who've said that the WBMG had no real connection to the rest of the show, although it had a certain play-along factor.
At the risk of accusations of Mo' Money Syndrome, I offer my GameTweaks (Pat. Forever Pending) that I believe would have improved the Shopping format (after all, they did get rid of it on the daytime $ale, didn't they?):
1) After the champion has been declared, (s)he would get a chance to win extra cash by playing a form of the Instant Cash game that eventually replaced the third Instant Bargain. The champion would automatically "risk" all but one dollar of the winning margin (ex., if the final score was "John $68 - Mary $88* - Bill $40," Mary would "risk" $19, and the scores would read "John $68 - Mary $69 - Bill $40.") The champ would then select one of however-many boxes, each of which would have a single piece of currency (ex. $1 - $2 - $5), and the "risked" money would be multiplied by the value of the bill chosen. (ex. if Mary found the $5 bill, 19 X 5 = $95, $95 + $69 = $164 to shop with. As you can see, it's not really a risk, since one could do no worse than break even.) This would give a new champion a shot at something better than a prize that, in many cases, was only worth about as much as the third Instant Bargain.
2) (Don't worry, it's much simpler.) Do not retire a contestant who buys a prize. Just have them return as champion (unless they win the lot.) (I couldn't believe this one contestant I saw, who was so happy to take the first level prize and quit; Jim Perry seemed surprised that (s)he didn't want to climb the ladder.)
Esoteric Eric; as for converting the Winner's Board to a Concentration bonus round, my GameTweak would set a specific number of chances to match a prize (say, three pairs of numbers for a first win, four for the second, and so on) with the "board goes back" rule in effect for non-matching pairs (unlike $ale). Champs would retire upon clearing the board (at least three bonus rounds).
*EDITED at 8:35 AM PST to correct the math error; easier to just change the simulated final score than the rest of the equations. Thanks, Zach