Might implies possibility.


  She might be 28, but she very well could be older.


Would implies intent.


  My parents would have walked along the Barrow had they lived by it. 


I don't think either of your statements imply doubt of any kind.

Usage of "might" and "would" to indicate doubt
I tend to stay at smaller boutique hotels or local apartments when I visit a city but recently due to some credit card issues I will need to depend on prepaid Visa.  But I noticed when I try to shop online a lot of retailers don't accept prepaid credit cards so I'm thinking hotels would be even stricter.  Is there a list somewhere of countries or particular hotel chains than ban prepaid cards? If so, how does one book online or reserve a room without a card?  Do all hotels worldwide accept cash?
