I am a federal employee with a TSP account. Thank you for your service. It is wonderful to hear that you and your husband are both maxing out your TSPs, have no debt, and have accumulated cash to invest. You wrote that you are “not knowledgeable enough to do day trading.” I think it is questionable whether anyone is knowledgeable enough to do day trading!
You didn't say exactly what your goal is, but it appears that you want to save for retirement. You stated that you wanted index funds or something simple. With that in mind -- and to make things very simple indeed -- you could choose a 1-fund portfolio (actually, technically a 2-fund portfolio): Lifecycle 2040 (or whichever date is most appropriate for you) in TSP and VFORX (or whichever date is most appropriate for you) at Vanguard for your taxable/Roth IRA accounts. And the nuts and bolts of your strategy could be as simple as maxing out TSP and Roth IRA contributions every year and putting as much into the taxable Vanguard account as possible. I'm not saying you should do that, but it is an example of just how simple an IPS [one suitable for a wide array of situations] can be.
I like the plan to invest $70k or so of the $120K cash you have on hand, and to keep $50K or so in a bank account. We live in uncertain times, and you wish to have kids soon, so the cash buffer would give you some peace of mind, as well as money to throw at problems that arise.
I do not understand this: “He does the same amount but does not have it set up as a Roth or a traditional IRA account. Does anyone know if he could switch his money into a Roth or a traditional IRA?” Do you mean he contributes to his TSP like you do? What do you mean by “switch” his money into an IRA?