From the partial snapshot you provide, I get the impression you have a fairly well-run household. There are a few points to make around the edges, but beyond that it is hard to give much more advice without knowing your overall spending picture and without knowing your overall goals. If you are hanging around a website like this one, a person might guess it would be FIRE, in which case an $110,000 annual family income should be able to get you from your current position to FIRE in about 5-7 years if you buckle down.
To your specific points:
For 401ks, I would suggest making deductible contributions at least until you clean down your 22% tax bracket. After that, it is a bit more of a toss-up whether you stick with deductible or Roth contributions -- depends on your long-term plans and outlook. A 12% tax rate is not a big deal whether you pay it or whether you save it; maybe state income taxes add a few points and make a bit of a difference. I would guess you could make $5,000 to $10,000 worth of deductible contributions per year to clean down your higher bracket, but you should run your own tax estimations on the new code. Read up on the investment order posts here, but in general I would not suggest paying down that mortgage before you max out all your tax-advantaged accounts to the best of your abilities (401ks, IRAs, HSAs, state-tax deductible contributions to 529s, etc.). At 4-1/8% interest, logic dictates putting more in 529s and taxable brokerage accounts before paying off the mortgage, but if you are hoping to FIRE sooner rather than later you might be more comfortable with a paid-off house.
I'm a bit of a "keep it simple, stupid," sort of person, so I simply keep a lot of cash on hand as an emergency fund and buffer for periodic expenditures (I don't spend a lot of time setting up precise sinking funds for my next used car or other things like that). The undersized emergency fund coupled with an undrawn home equity line of course makes logical sense as you have a bit more in the market earning dividends, but I always worry about the behavioral aspects of such arrangements -- will I somehow trick myself into overspending if I set up something like that? Also, without your spending record, it is hard to say whether $30,000 is even the right number -- it works out to $5,000 a month for six months, which is not absurd but still a pretty high cash burn rate around here.
Regarding college savings, $17,000 should certainly double (if not more) by the time college rolls around, but that's certainly not enough to pay for 8 years at full freight, so it is a question of your long-term goals: Do you expect the kids to commute from home to a local state college and pay in-state rates? How much do you expect to pay yourself, as opposed to the kids working, receiving financial aid or taking out loans to pay for their own educations? It might be perfectly reasonable to stop saving now; it depends on your goals.
So far so good, but again: To be able to say much more it would help to have some insight into your saving / spending habits.