wifi extenders

We just got a new Pre-Paid phone plan with AT&T (8GB each on two phones per month). I'm sure Verizon has something similar to what we're going to do. We posed the question about using our phones as a hotspot. It was suggested to us that we have a plan at home that gives us what we need and not more but when away for the winter, upgrade the plan to the unlimited plan and then downgrade it again when we return home. I asked how often we can do that and were told we can do it as often as we want. That way we only pay extra when we need it. Something to look into anyway.