I've always thought had the liberal hawks in the CIA prevailed, Castro (who didn't mention the word Communist for his fist few years in power) could have easily been co-opted as an American ally.
American foriegn policy throughout the Cold War was severly hampered by a very US-centric, conservative view towards nationalist/liberation movements in the third-world, namely seeing any effort to strengthen their country (inherently being nationalisation of crucial Western dominated industries) as signs of Soviet influence. Something which did the Americans major harm or at least irritation in the long-run through the "They may be bastards, but they're our bastards" policy. Noriega, Mohammad Shah, Saddam, Pinochet to an extent, all sketchy to put it mildly but less worrying than left-leaning democracies. Only to have them range from embarrassing to security risks to full-blown regional destabilisers.
Hell Ho Chi Minh was trained by the Soviets and even he looked to the US for support and aide before they started backing the French in Indochina.
So back to the question: From what I've read, had the Americans been more open to negotiating with Castro's new regime and swallow at least part-nationalisation of previously American dominated industries, Castro would flat have stayed away from Moscow. He is (or was depending on how effective you believe Cuban State misinformation is) a pragmatic, power-hungry man. Let's be honest, do you think Castro really thought he could last long as an out-and-out enemy of a global superpower, right next door?
I have no doubts he would have jumped at US recognition for a sensible price. How Cuba would look today is debatable. It would be the Jewel of Latin American tourism, as continued American influence means continued mob influence and that means Casinos by the dozen. Whoever mentioned Rio as a parrallel is on to something IMO, Cuba's large middle-class and the island retaining even a fraction of its heavy American investment could see Havanna become a bustling commerical centre, albeit one surrounded by major poverty. Politically I think at least for some time Castro would retain a Mexican-style "one-party democracy", though considering the large, quite westenised middle-class Cuba had I'm not sure how long such gerrymandering and populism would last, again some more idealist US President might object to it, or more cynically tire of Castro for one reason or another. Cuba's welfare would certainly be more limited though I can see Castro pushing for some grand gesture like Universal Healthcare at least. This might be easy as the proximity of America could see a training cycle comparable to Indian doctors working in the British NHS.
All in all I think Castro's Revolution or something equally ground-breaking is needed purely to upset the Banana Republic system of government. Despite what some rightly upset Cuban emigres say, no Castro certainly doens't equal democracy and plenty.
