I would only go for these reasons:
If you're not 100% sure Western is for you
If another school offers a unique format (I know some of the Erie schools do PBL so it may be interesting to see if you think PBL is a better fit for you)
If the school is generally considered to be a much better school than Western, I get the impression that Des Moines is pretty amazing and has a great reputation, plus I hear their anatomy lab is the best for any osteopathic school.
Also, cost there is a "Cost of DO Attendance" excel floating around SDN and they have Western cost without living expenses to be upwards of $40,000 for next year (I believe it is one of the most expensive DO schools). So, if there is a solid difference in cost between Western and another one of these schools, then I would go to the interview and check it out.
One thing to consider about Touro CA is that if you are accepted they require a $2,000 deposit to hold your spot in the class within two weeks of acceptance. This deposit is non-refundable, so getting an acceptance at TOURO CA will force you into making a decision rather quickly.
Ultimately, it's your decision and it's about where you think you'll fit best. I've been accepted to TOURO CA and I like it so much that I'm not going on any other interviews, unless I get offered an interview for my in-state MD schools b/c they have better pathways into oncology and the tuition is so cheap that it's worth it to try.