If you are not sure what you can invest with your extra savings, you can put money in your house payment. 30-year will provide one flexibility of paying some money for principles. This will shorten your payment time too.
if your rate of 30yr loan is less than 1% higher than 15 yr loan. you are fi ne. otherwise, stick to your 30yr loan. also, if your equity is less than 75% of property, u may not qualified for a ny refinance.