Deborah Ann Woll, (True Blood), for May Parker. She has the girl next door appeal, and is on par with the great Amy Adams in terms of acting.
Jason Bateman for the middle aged Peter Parker. His demeanor is perfect for Peter balancing fatherhood and the heroic antics of his past. Plus, his comedic touches are perfect for a family friendly/borderline action series.
Amy Adams for the middle aged Mary Jane Watson. Watch her in any role. She's got the perfect witty, flirty attitude with great acting ability and a wide range of roles to support it.
Normie Osborn, JR, played by Supernatural's Jensen Ackles. As it happened in the series, Normie seeks revenge on the Parker family, after escaping from the Asylum he was locked up in, for the death of his father. For season 1, he will be the main villain, but a sympathetic one. May Parker is convinced he can be saved. And that will be part of the theme for season 1.
Óscar Jaenada as the Black Tarantula. A manipulative, South American crime lord, and a sociopath. He is secretly building his crime cartel in New York City while courting May Parker and trying to destroy her as Spider-Girl. He is the major villain of Spider-Girl and the temptation of May Parker. May has no idea he is the Black Tarantula nor does she know he knows she is Spider-Girl. He's the one that sends the villains after her. He's testing her as Spider-Girl to make sure she could be a worthy bride one day. He is Mays blind spot even when her friends try to warn her, it falls on deaf ears.
Carl from The Walking Dead for Ben Parker (forget the lack of Ben's picture). In this show Ben would be around ten years old and be May Parker's help for the science aspects of the universe, as he takes after his father with gifted brilliance. He is determined to help his sister and she is determined to keep him safe, not an easy job as Ben's powerfully curious mind often leads to trouble.
Jenny Humprhey for Felicity Hardy. On google search someone else made this suggestion and I think it is perfect. I would like too have her as a new version of the Black Cat rather than Scarlet Spider for the TV Show. Felicity comes to live with the Parkers after her parents, Felicia Hardy and Flash Thompson disappear after a plane crash, and their bodies were never recovered. Once Felicity discovers Spider-Girl, she takes up the mantle of Black Cat as a prowler to find out information about her missing parents.
Kristin Bauer from True Blood for the older Black Cat. She would appear in flashbacks and later on in the series, once the story of their disappearance has been resolved.
Thomas Haden Church for the older Flash Thompson. A great actor, for a role that will eventually turn up majorly.
There are other characters that can be introduced but I believe this could be a good start to a weekly television series.