I know of Gator Guns at 2489 N Military Trail (West of I-95 off Okeechobee Blvd). They do have some older shotguns under glass, but the taxidermy display is wonderful. Talk about tons of displays including a pair of fighting lions. Not the friendliest (the staff, the lions are dead) though the gunsmiths in back are neat to speak with. Do so (with ther gunsmiths), just walk in and say hi. Dewing's has closed and I'm not sure if Mike Burton (ex-sales at Dewing's) opened up his place at City Place (the outdoor mall to the East of I-95 on Okeechobee Blvd).
Other stuff - For full auto you can't beat Only The Best Firearms at 230 S Cypress rd., Pompano Beach. He's got most behind the wall now but you can ask for those Thompsons, MG34, all HK variants, Sterlings Stens etc.
You can check out only this weekend the Palm Beach Convention Center for $20 at 650 Okeechobee Blvd. (East of I-95). They have the Intl American Fine Arts Exhibit. Look for Peter Finer Antiques who are exhibiting, though not having shotguns they have some phenomenal pistols incl a pair of cased dueling Mantons, swords, etc. The fair is neat because of the paintings (old masters, contemporary etc). They have Nick Brandt works there (huge photograph originals of African Animals). There is a fine documents gallery exhibiting George Washington's copy of the Federalist papers book and so much more. Cool stuff if youre looking for something different.