Wow, marginal rates in the 90%+ range in the 40s, 50s and 60s and the 70% range in the 70s !
I should think about converting more to Roth at the current rates.
OP, Tax-loss harvesting, tax-efficient placement of your investments (see bogleheads wiki), HSA are the main ones. You should be glad you are not earning in CA or some other high income tax states. Could be 30K addtl tax.
Also note, you are not paying FICA of 6.2% above about 110K salary each, so your marginal tax rate could actually be lower than a couple making ~110K each.
Business income (schedule C) is unlikely to be of much help. You will need revenue to write-off some expenses to not get flagged by IRS. The tracking, time and energy you put into saving a bit in taxes setting up a business is better put in increasing your salary at your jobs. The goal of more $ in your pocket, not less $ in govt pockets is better for you personally.