Here are a few options for you:
1) You can sell your house and buy a smaller one, since you would like to move somewhere smaller, or rather, a one-story house. If your house is worth 535K, you might be able to take the cash you get from selling the house and buy a new one outright. If you have extra cash left over, you can invest that and make it work for you in a way such that it supplies extra monthly income for you guys.
2) You could refinance for 30 years, lower your monthly payments to $760, and live there long enough to recoup the costs, which is only a few months depending your closing costs. If you live there for a few years, you can get a smaller home with the cash you get from selling your house + the extra cash you'll be saving per month.
3)
If you are absolutely sure you are going to move within the next 5 years, you could get a 5/1
Adjustable
Rate
Mortgage. This will bring your APR into the 3% category, and you'll have super low monthly payments for the next 5 years. The savings will easily be recouped within a few months since the difference in monthly savings will be huge. When you're ready to move, you can use the cash from selling your home and the cash from your monthly savings to buy a new one.
The differences between option 2 and 3 are the window of time you have to make your choice to move or stay and the APR. Once the 5 years is up, your interest rate on the ARM will jump all over the place. It could even jump to the point where you can't afford the payments and you end up losing your home. Use this option only if you are sure you are going to move within the next 5 years.
4) You could refinance for 15 years and lower your payement by a few hundred dollars a month. You'll end up paying a lot more interest if you end up staying in your home for the full 15 years, but you'll have that option and make lower monthly payments, which will be nice when your income level drops.
5) You could do nothing and stay in your home. Since you guys are at the retiring age, you'll be able to dip into your 401k, IRA, 403b, etc without penalty. I'm also assuming you will be getting social security, so that might be enough to get you guys by through the next 11 years. Keep in mind that if you guys end up buying another home and owning it outright, none of this money will go to a mortgage.
Good luck.
