The trick here is being able to obtain a B2 visa since that's probably your best chance of being able to stay here 6-months at a time.

However the Visa's can be harder to obtain due to the more extensive tests that are carried out. The USCIS wants to be comfortable that you have a permanent residence in your home country and that you're not looking to stay here. Proof of this would include showing that you have very strong connections to your home country and that you are financially independent and have no plans nor desires to become a resident of the USA (illegal or otherwise).

Finally there is never any guarantee that a B2 would be issued or for how long you'd be allowed to stay here and if the officer at the port of entry feels the Visa's been abused he's within his rights to limit or even deny your visit.

Given that there is no 'retirement' visa for the USA, using B2's for snowbird retirees is an option albeit a slightly risky one.