Concrete Site or Sand and Grass

We've narrowed down our search to three RV parks/Resorts for next winter. Two of them are grass/dirt with concrete pads and one is an all concrete parking and pad area with some grass between sites. We like all three places but as with anything, there's pros/cons with each of them. All are about the same money when all things are added in. My main concern is Fire Ants and other types of small critters that will find their way in if given half a chance. The fewer issues we have to deal with the better. Next winter will be our first as snowbirds so we are trying to think about as much as we can and hopefully avoid a lot of "you know what honey? We should have done this or that"