I have stayed at only a couple HGI's but the breakfast is free and (IME) much nicer than a FI/SHS breakfast.

I recently stayed at the HGI Frankfurt airport and it was excellent, and right in the terminal (10 minute walk).

The nearest Marriott property (I believe) is the FS Frankfurt, which is a 20+ Euro taxi ride each way. Great hotel/lounge, but for a short layover, staying at the terminal is nice.

I try to avoid CY's except the "boutique" ones e.g. San Diego.