Laura and her husband run a wonderful BNB in the middle of Lido Ostia. They were accommodating, friendly, provided excellent recommendations, and provide breakfast in the morning.
The room is spacious and comfy with a balcony (we were here in the winter, but would be an awesome place to have coffee in the spring or summer).
You're right in the middle of things and are readily able to visit the sea or the restaurants downtown.
Parking can be a challenge. There's a free lot where you can leave your car for free overnight, though it's unsupervised.I wouldn't leave things in your car. (Search in google maps for 'Area do Parcheggio' at 195, Via delle Baleniere, 175, 00121 Lido di Ostia RM, Italy).
Thanks again!