Welcome to the forum, BruceH_HydePark!
The TripAdvisor Iowa forum is little visited. I doubt you will find anyone who has stayed at both the AmericInn and Boulders Inn and contributes to this forum. I can only suggest that you check the TripAdvisor reviews. I do not know why Boulders is listed on TripAdvisor as a B&B, it looks like a normal US motel.
The Newton AmericInn looks better than what I remember of the chain. If I had to choose one motel and the prices were similar, I would stay at Boulders. Boulders is part of a small Iowa chain, is newer (if reviews can be believed) and does not allow pets. AmericInn has an indoor pool and allows pets.
-:- Message from TripAdvisor staff -:-
This topic has been closed to new posts due to inactivity. We hope you'll join the conversation by posting to an open topic or starting a new one.
To review the TripAdvisor Forums Posting Guidelines, please follow this link: http://www.tripadvisor.com/pages/forums_posting_guidelines.html
We remove posts that do not follow our posting guidelines, and we reserve the right to remove any post for any reason.