So cash out refi will get you lets say 30k cash at about the same rate, as a cash out loan is a bit higher rate and rates are up .375 since they hit bottom 2.5 weeks ago. (bottom this time around)
Personally I hate throwing student loan debt into your house. In fact, it is illegal for a loan officer to suggest it. (credit card, personal loan, car, etc all legal, but student debt already tax deductible, etc).
See if you can find a better rate on your student debt. How old are your kids? How old are you?
To me I would work on paying off the student loan debt on its own, not lumping it in with other debt. Also, you need to think of your own retirement, you want a paid off mortgage at retirement, and even if this isn't your retirement house, the more equity you have, the better chance you owe zero on the house. And the less you owe total, the more you can help with college as you go, so once again don't roll it into your house.
And to me the biggest gift you can give your kids is not to pay for college, but to not be a financial burden on your kids when you retire and they have a young family, once again the way to a healthy retirement is a paid off mortgage.
For so many reasons I wouldn't take out a mortgage to pay off the student loans.