I've worked at both and probably of the two, Broadway at the Beach especially to see Bruce at night in front of Klig's Kites. He's hilarious.
If dining and live music is what is going to sway you, then Barefoot Landing. Their restaurants (Greg Norman, T-Bone, Flying Fish, House of Blues, Dinos, Umbertos, etc) are far superior to Broadway's in my opinion. This time of year you'll never get near Margaritaville but King Kong Sushi has the best sushi in town.
Fireworks every Monday night at Barefoot Landing and Tuesday night at Broadway At The Beach.
The best shopping and dining however is hands down at Market Common. Check the website (
www.marketcommonmb.com) to see if they have fireworks or a special concert/event.
Come to think of it, it may just be a wash between Barefoot and Broadway. Go to whichever is closest to you.