all depends on how a field is going to be used.  If it's basically a game field only - no practice, etc - then a grass field can hold up pretty well.  but if you're playing varsity, JV, Junior High, Boys Soccer, Girls Soccer and so forth, then a grass field will get beat up - especially if you have a couple of "rain" games. 
in Windom, where I live, the School Board is floating a proposal for a new sports complex - in order to move the games away from the river that keeps flooding.  the plan would have a multi-use turf field, plus new baseball and softball fields next to the high school, re-doing the HS track and field complex, along with renovations to the locker rooms, a new wrestling practice area, and a new performing arts facility.  estimated price tag is $33-million.  the "Ag2School" tax credit will lower the net cost, but it's still a big number for a smaller community.  (4,800 people).  they are applying for grants, hoping to get some FEMA money - and - no joke - offering 'naming rights' for donors.  So if you want a football field named after you and can write a check for 7-figures, contact the Windom School District.