Unrelated Co-Owners Buying

I'm not a lawyer, and you will want guidance from a real estate attorney.  My guess is that a corporation isn't necessary and that some sort of simpler co-ownership is what your attorney will suggest.  Some questions to be considered and discussed ahead of time, and incorporated into some sort of written agreement:

How is use of the property going to be divided--who gets to use it Labor Day weekend?  If one partner dies, should ownership go to the others automatically or can it be disposed of to outside heirs by will?  If one partner wants to sell (perhaps, for example, with a job transfer across the country), can that share be sold to an outsider or must it be offered first to existing co-owners?  What would be the basis for a sale price?  How will the group arrive at decisions about maintenance and repairs?  What if one co-owner cannot or will not bear a share for expenses? 

The there's the possibility that one co-owner's financial troubles, perhaps judgments, could result in liens against the property.  Maybe that's why you are thinking of a corporation, but at any rate, your own lawyer is the person to give you information on that problem.