I dont think you should feel guilty at all, I work at a long day care centre and can tell you that there is alot of SLACK dole bludging parents who put their children in full time care when they are at home watching Jerry Springer. All the staff feel for the hard working caring parents who are forced into care. Make sure you throughly check the centre out and feel comfortable with the staff because I know from exprience that there is some really low quality centres with incompetent staff.
I wouldnt recommend visiting during the day though as it upsets the childrens routine and makes seperation harder on both of you