Where can I find a list of museums where I can use my .membership?

This Museum participates in the: ASTC Passport Program - https://www.astc.org/passport/ ACM(with the Wonder and higher levels) - https://childrensmuseums.org/members/member-benefits/acm-membership I strongly suggest you consult these websites and your home museum's/destination museum's policies on reciprocal benefits before traveling. Pay close attention to the benefits and limitations at each.

I was just in the Fort Worth area and was able to find everything I was looking for using Google.

I would just Google it. The the best way to fine what I need.