I keep mine floating about 1/16-1/8" on all my strats, depending on the string gauge I'm using. I prefer the sound from the floating trem and never really noticed a big difference when it was flush. I've never had tuning problems with a Fender and floating trem. I lubricate the nut with graphite, set it up to Fender specs, and stretch the strings real good when I change them. It seems to work.
Guitars: 2003 and 2004 American series strats, Squier Classic Vibe 50's Strat, Squier Deluxe Strat.
Amps: Line 6 Spider IV 120, Vox AD50VT 212, and Peavey Transtube Bandit 112.
Pedals: Digitech Bad Monkey.