Bird In Hand, if I were you, I'd go with the HDHP plan. In fact, my family DOES use my husband's HDHP plan, and my employer covers whatever it doesn't, leaving us to fill the HSA to the brim and keep it, which has been a huge boon.
ctuser1 talks about the First Dollar rule, but I'm not sure how your employer could offer a "HDHP plan + HSA" (that they contribute to, no less) only to have the HSA be ineligible because of the way the HDHP works. I think this is only an issue if the HDHP doesn't come with the HSA option and you're trying to invest in an HSA on your own with a separate administrator.
@ctuser1 , can you educate us about this?
Actual IRS Rule discussing HSA eligibility and limitations:
https://www.irs.gov/publications/p969If a single employer offers both HDHP + HSA, they will probably make sure the plan is compatible with HSA. First dollar rule typically only comes into play when you have coverage options from multiple sources. e.g. both spouses working, or when you work but also eligible for medicare.
To be eligible for HSA, you need to have "high deductible" that you pay out of pocket. You can not have any kind of plan that pays you from the very first dollar of your cost. e.g.
1. FSA that can pay you from the first $$ of medical expenses.
2. Another PPO health plan that can provide partial coverage (say 80%) from the first $$.
3. HRA (like I mentioned my wife had) that pays 50% of each $ spent from the first $$ expense.
etc.
All these are explained in the IRS publication I linked above in much more detail.
In fact, when you say "and my employer covers whatever it doesn't", it is a situation where it's important that you are not inadvertently making yourself ineligible for HSA. The "Other health coverage" section in the publication I linked above might be relevant here.
Note: I am not a professional dealing with this topic. I have just used HSA under many different scenarios for over a decade and hence only know details of some of the scenarios that I encountered. Please don't mistake it as a substitute for professional advice.