Honestly - I read it in various forums and some travel books. Even ricksteves gives a warning. Or maybe it was lonely planet, I can't remember. Going to post my trip below for reference since everyone so kind to respond to me.
To sum it up: St. Petersburg is UNBELIEVABLE. Needed to share with the community.
Oct 3 (arrived around 3) and left October 7. I would give yourself atleast 3 full days. We had roughly 3.5 and were able to do it all.
Safe, absolutely gorgeous, clean, fun and many great sights to see.
Safety: Was never really worried at all. I was hypervigilant because the thought of an American going to "Russia" and some of what I read indicated I should be. I kept a small amount of money in my pockets along with my phone, everything else is locked away in my backpack (as it always is no matter where I was traveling). I had no issues whatsoever. I DID carry our passports with us at all times.
Border/Customs official were polite and laughed with us. We took the train from Helsinki, Finland (Awesome, fast, clean, english speaking train employees). 99% of the people were extremely nice. Learn a little bit of Russian, it goes a long way.
I used uber 99% of the time, no issues, even though some drivers do drive like lunatics. Extremely cheap to move around the city. Request pickups on streets away from Nevsky, way way too congested.
The only minor issue I had was as follows (was rather funny): Our uber driver picked us up, I greeted him as my girlfriend and I entered his car. He then proceeded to say something in Russian, so I said in Russian back, "I am sorry, do you speak english?" Obviously my Russian is horrible so that coupled with me asking him if I spoke english prompted the following response (atleast what i could make out)
"F*** English/Americans?"... My girlfriend got nervous... I laughed, and said, Nyet - ya lyublyu St Petersburg! He smiled and laughed back. Ya lyublyu means "I love".
He then proceeded to teach me some Russian on our drive back. All was good. I asked many many people the same question, they all smile back and know a little or indicate they dont know any english.
Puklovo Airport: Beats JFK. Its certainly smaller, but has a brand new main terminal. Plenty of places to eat/shop/relax before your flight. Very smooth and easy through customs/security.
Transportation within St. Petes. This city is MASSIVE. We walked, but took alot of ubers. The subway is efficient and fast but uber was so cheap it was a no brainer.
Food: One of the best restaurants I've eaten at Mansarda. Pricey, but worth it. View looking at St Isaacs Cathedral. Other restaurants were good but nothing special.
Hotel: W. St Petersburg - Worth every penny. Location is right in the middle of everything, the staff are hands down the best, rooms are great, and there is a ATM right in the basement which makes life easy.
Ballet: Mariinsky 2 is phenomenal. We saw the Giselle ballet, unbelievable.
Bars/Clubs: Didn't go to any clubs here, the one I was interested in was far away. We did go to a few bars close by and grab some beers. We never stayed out past 12-1, was getting cold at night.
We did a few tours when we were there. Used Russiantrains.com to book canal tour and dancing bear tours for a private tour of Peterhof/Catherine Palace. (No brainer, go to both of these)
Also used Peterswalk for a walking tour of Hermitage and around some main sights. Did not fail to impress, they were beyond great.
Found it easier to do a tour here because of the language barrier, made it easier to learn Russian history.
So in conclusion, if your on the fence about going to St. Petersburg... GO!!!!!!!!!
US Dollar is strong against the ruble, it goes a long way.