I agree with others that choosing a convenient location is important.

In addition, I think you need to consider other factors with each of the properties as they relate to your personal needs. For example, if you want free breakfast and/or free internet, your HH Gold status provides that, but without status, you are unlikely to get these benefits at other chain's full service properties. Marriott Residence Inn provides free breakfast and internet (I think) to all guests, but has reduced points earning (half of full service Marriotts)

You also need to think about this trip in conjunction with your future travel (both to earn more points and in terms of how you want to use points). For example, you mentioned Marriott's Megabonus offer, but that only will be valuable if you have another paid stay planned during the promotion period, and have plans within six months from the MB end date to stay in a Marriott category 1 - 4 hotel (assuming the MB terms haven't changed; I have not looked at the T&Cs of the current one).