We're planning on converting his 401(k) to Roth IRAs during that time up to the 15% tax bracket before RMDs kick in. We're also planning on selling our home and using that money as "income" for those years and stop dividend reinvestment once he retires. This will allow our other investment accounts to grow.
One, how does the above plan sound?
It really depends on a number of things, including your current investment balances, the value of your home, your current expenses, and the expected rent you would pay after selling your home. We need more information to give informed advice.
In broad strokes, I might hesitate to sell the home if it's in the area you want to retire in and isn't way too large for two people. When you sell your home your expenses will go up because you'll need to add rent into the mix. This will be a permanent expense increase, just so you can have some more cash on hand before you start taking social security. The fact that you even mentioned RMDs indicates you think you'll have savings left over when you start taking your social security, and you already said your social security and pensions will be enough to cover current expenses after that, so why sell the house now?
Your situation sounds fairly similar to my own parents. They retired slightly early by normal standards, but they didn't need to plan for their savings to provide for them for a couple of decades prior to social security like many of the people on this site. There are basically three phases they need to plan for:
1) Time to spend savings before social security,
2) Time they're both taking social security, and
3) Time after one spouse passes away and only one is taking social security.
It sounds like you're all set for phase 2. Your social security benefits and pension will be more than your combined expenses. How about phase 3? My understanding is that the way "widow's benefits" work is basically that when one spouse passes away, the surviving spouse gets to keep the higher of the two social security benefits, but not both.
Don't fall into the trap of spending all of your savings during phase 1 so that you're dealing with a budget deficit in phase 3. I've been trying and trying to get my parents to invest more of their savings precisely for this reason. They see that they have plenty of cash to see them through phase 1 and are hesitant to take any market risk with this money, but I cFIREsim shows it's actually riskier in the long run for them not to invest because they will need their savings to grow some during phase 2 to provide enough for phase 3. If the surviving spouse still has quite a bit of life expectancy left when this happens, this is when having a paid-off home could be really helpful. Selling it would be your backup plan in case one of you meets an early demise and your remaining savings aren't enough otherwise.
Two, does anyone know how to calculate SS amounts when we quit work earlier?
In your case the number on your social security statements are probably pretty close to accurate. The system calculates your benefits based on a couple of income bands, such that once you pass a certain threshold of lifetime earnings your benefit won't go up all that much when you work more. This is especially true if you have earned money in at least 35 separate years, as new higher-earning years will simply replace lower-earning years in the calculation so you only get credit for the difference in pay between those two years (in inflation-adjusted dollars).
If you really want to calculate it anyway, the Social Security Administration has
a program you can download that might be worth a try.