I lived in Imabari for 2 years and my husband and I stayed for one night before doing the Shimanami Kaido. While the hotel is well located for the port and downtown area, there is little around to offer foreign travellers, and the hotel staff don't speak English (I speak some Japanese). We tried to arrange to get our luggage transported to our next hotel (in Kurashiki, one hour north of Onomichi) but despite the information available on the Internet and my previous research, we were informed that we could not get it delivered on the one-day service to Kurashiki, and it could ONLY be transferred to Onomichi, and ONLY to a hotel on their list. As we didn't have a booking in Onomichi we tried unsuccessfully to get the staff to arrange an alternative for us. While the lady at the front desk went out of her way to help us, this couldn't be arranged and we were forced to make a cheap hotel booking in Onomichi just to get our luggage delivered.
I give this advice to anyone wanting to arrange hotels in Imabari/Onomichi, who is wanting to do the bike ride and get luggage transferred, especially if you do not know any Japanese language, as there is little English spoken by people in Imabari.
Apart from this stress, our stay was fine. :)