「すごいすごい。[初]{はじ}めてです、[広島]{ひろ・しま}は。」 is not wrong, but if you are a man, it's a little strange, because 「すごいすごい」 is a phrase that a girl says, usually (if it has a positive nuance). If you want to emphasize すごい, すっごい would be more natural to use than すごいすごい. すっごい is commonly used by both men and women.
「すっごい初めてです！」
is naturally said in casual conversations by some young people. It means "This is my very first time!"
「めっちゃ初めてです！」
has the same meaning, and used by many people.
です is keigo, so 「すっごい初めてです」 and 「めっちゃ初めてです」 are nice ways to say, but they sound somewhat casual.
「まったく初めてです。」
is polite and more common, so this can be used in more various situations.
If you feel 「初めてです」 is too simple,
「初めてなんです。」
may fit your needs. This なん confirms the meaning of 初めてです. It's like saying "This is definitely my first time."
The は of 広島は is not necessary.
「初めてです、広島。」 or 「初めてなんです、広島。」
sounds natural.
When some distinction is needed to express, は is useful. For example,
「初めてなんです、広島は。[大阪]{おお・さか}は[二三度]{に・さん・ど}[行]{い}ったことあるんですけど。」
(This is definitely my first time in Hiroshima. I've visited Osaka a couple of times, though.)
If you want to say something positive about the place but don't want to specify what, 「すごいところですね。」 is a nice way to say as mentioned in the comment by The Wandering Coderさん. Or,
「いろいろすごいです。」 or 「ほんと、すごいです。」
would work well. In this case, saying a 初めてです sentence first would sound more natural. For example,
「初めてなんです、広島。いろいろほんと、すごいです。」
About the Florida sentence, the following example would sound more natural and relatively understandable for native Japanese speakers.
「ここ[来]{き}て[突然]{とつ・ぜん}[花粉症]{か・ふん・しょう}が[酷]{ひど}くなっちゃうし、もうとにかく[暑]{あつ}くて。しかも、初めてなんです、[フロリダ]{ふ・ろ・り・だ}。」
