What are my options other than "The Big Four" (Cellular Service)

[Ombligo]

You could use a less expensive limited data plan for yourself and then a high usage plan for her. My wife and I are with Puretalk for $15/month combined but neither of us needed data. My son lives on Data, he uses Straight Talk at $45/month for unlimited test/talk and 5gb of high speed data (then unlimited throttled). So that is %60/month for three and we are all happy.

my point is, you don't have to both be on the same carrier.