Guam Airport provides a very spacious room with a full kitchen. It is good for extended stays on Guam. The staff are helpful and friendly.
Just remember a few things:
You're on Guam, it's a tropical island with tropical plants and, yes, insects too. Don't freak out if you find a gecko sitting on the porch :)
If you can't afford to pay $200-300/night for a hotel, don't expect a five star hotel. What you will get is a clean, affordable hotel room with friendly service.
I world recommend this hotel to fellow long term travelers.