Welcome lulu
You are right to wonder if that money could be put to better use, but you should not be ashamed to be in what sounds like a very good financial situation.
Now - how to put that $150k to better use...
For starters, keep whatever amount you need for an emergency fund in that savings account. Typical advice ranges from 3-9 months worth of expenses, but it can be less or more depending on your situation (e.g. job security, tolerance for risk, potential for unplanned expenses, etc).
You mentioned you are already maxing out your 401(k)s - good job! and that think you might be above the ROTH IRA limits. A few things to check on;
For taxable accounts:
1) do you have an HSA available to you? If so, max that out
2) use the "
backdoor roth" method to contribute money to a ROTH IRA
3) if your plan allows it, do a
mega-backdoor ROTH.
After you have explored those options, it's time to start saving in taxable account.
Typically around here a low-cost index fund is the most popular choice. I'm fond of the SP500, though others prefer the total market index or a blended fund that contains some porportion of stocks and bonds.
It's important to have an
Investor Policy Statement (IPS) and to stick to that plan. An ISP doesn't have to be complex; I can write mine on an index card. But it keeps you from chasing hot markets and gives you a plan on where to put your money.
I hope that helps; feel free to ask for clarification if it didn't.